diff --git a/public/app/containers/AlertRuleList/AlertRuleList.test.tsx b/public/app/containers/AlertRuleList/AlertRuleList.test.tsx
index eac18a6c69d..f88ff4522d4 100644
--- a/public/app/containers/AlertRuleList/AlertRuleList.test.tsx
+++ b/public/app/containers/AlertRuleList/AlertRuleList.test.tsx
@@ -46,7 +46,7 @@ describe('AlertRuleList', () => {
 
   it('should render 1 rule', () => {
     page.update();
-    let ruleNode = page.find('.alert-rule-item');
+    const ruleNode = page.find('.alert-rule-item');
     expect(toJson(ruleNode)).toMatchSnapshot();
   });
 
diff --git a/public/app/containers/AlertRuleList/AlertRuleList.tsx b/public/app/containers/AlertRuleList/AlertRuleList.tsx
index 3c2da77c2a7..668136dee6f 100644
--- a/public/app/containers/AlertRuleList/AlertRuleList.tsx
+++ b/public/app/containers/AlertRuleList/AlertRuleList.tsx
@@ -132,13 +132,13 @@ export class AlertRuleItem extends React.Component<AlertRuleItemProps, any> {
   render() {
     const { rule } = this.props;
 
-    let stateClass = classNames({
+    const stateClass = classNames({
       fa: true,
       'fa-play': rule.isPaused,
       'fa-pause': !rule.isPaused,
     });
 
-    let ruleUrl = `${rule.url}?panelId=${rule.panelId}&fullscreen=true&edit=true&tab=alert`;
+    const ruleUrl = `${rule.url}?panelId=${rule.panelId}&fullscreen=true&edit=true&tab=alert`;
 
     return (
       <li className="alert-rule-item">
diff --git a/public/app/containers/Explore/Table.tsx b/public/app/containers/Explore/Table.tsx
index e5adde2d008..cbb3ab11f4e 100644
--- a/public/app/containers/Explore/Table.tsx
+++ b/public/app/containers/Explore/Table.tsx
@@ -40,7 +40,7 @@ function Cell(props: SFCCellProps) {
 export default class Table extends PureComponent<TableProps, {}> {
   render() {
     const { className = '', data, loading, onClickCell } = this.props;
-    let tableModel = data || EMPTY_TABLE;
+    const tableModel = data || EMPTY_TABLE;
     if (!loading && data && data.rows.length === 0) {
       return (
         <table className={`${className} filter-table`}>
diff --git a/public/app/containers/Explore/utils/prometheus.ts b/public/app/containers/Explore/utils/prometheus.ts
index f5ccb848f2f..19129976282 100644
--- a/public/app/containers/Explore/utils/prometheus.ts
+++ b/public/app/containers/Explore/utils/prometheus.ts
@@ -65,7 +65,7 @@ export function parseSelector(query: string, cursorOffset = 1): { labelKeys: any
 
   // Extract clean labels to form clean selector, incomplete labels are dropped
   const selector = query.slice(prefixOpen, suffixClose);
-  let labels = {};
+  const labels = {};
   selector.replace(labelRegexp, match => {
     const delimiterIndex = match.indexOf('=');
     const key = match.slice(0, delimiterIndex);
diff --git a/public/app/containers/Teams/TeamList.tsx b/public/app/containers/Teams/TeamList.tsx
index 2d037eed642..d0feee75184 100644
--- a/public/app/containers/Teams/TeamList.tsx
+++ b/public/app/containers/Teams/TeamList.tsx
@@ -36,7 +36,7 @@ export class TeamList extends React.Component<Props, any> {
   };
 
   renderTeamMember(team: Team): JSX.Element {
-    let teamUrl = `org/teams/edit/${team.id}`;
+    const teamUrl = `org/teams/edit/${team.id}`;
 
     return (
       <tr key={team.id}>
diff --git a/public/app/core/components/Permissions/AddPermissions.test.tsx b/public/app/core/components/Permissions/AddPermissions.test.tsx
index 513a22ddea4..c6d1ab381b8 100644
--- a/public/app/core/components/Permissions/AddPermissions.test.tsx
+++ b/public/app/core/components/Permissions/AddPermissions.test.tsx
@@ -22,7 +22,7 @@ describe('AddPermissions', () => {
   let wrapper;
   let store;
   let instance;
-  let backendSrv: any = getBackendSrv();
+  const backendSrv: any = getBackendSrv();
 
   beforeAll(() => {
     store = RootStore.create({}, { backendSrv: backendSrv });
diff --git a/public/app/core/components/TagFilter/TagFilter.tsx b/public/app/core/components/TagFilter/TagFilter.tsx
index 84f3e1819cd..a879f544da0 100644
--- a/public/app/core/components/TagFilter/TagFilter.tsx
+++ b/public/app/core/components/TagFilter/TagFilter.tsx
@@ -43,7 +43,7 @@ export class TagFilter extends React.Component<Props, any> {
   }
 
   render() {
-    let selectOptions = {
+    const selectOptions = {
       loadOptions: this.searchTags,
       onChange: this.onChange,
       value: this.props.tags,
diff --git a/public/app/core/components/code_editor/code_editor.ts b/public/app/core/components/code_editor/code_editor.ts
index 886ae2a6407..66aec778d73 100644
--- a/public/app/core/components/code_editor/code_editor.ts
+++ b/public/app/core/components/code_editor/code_editor.ts
@@ -53,23 +53,23 @@ const DEFAULT_TAB_SIZE = 2;
 const DEFAULT_BEHAVIOURS = true;
 const DEFAULT_SNIPPETS = true;
 
-let editorTemplate = `<div></div>`;
+const editorTemplate = `<div></div>`;
 
 function link(scope, elem, attrs) {
   // Options
-  let langMode = attrs.mode || DEFAULT_MODE;
-  let maxLines = attrs.maxLines || DEFAULT_MAX_LINES;
-  let showGutter = attrs.showGutter !== undefined;
-  let tabSize = attrs.tabSize || DEFAULT_TAB_SIZE;
-  let behavioursEnabled = attrs.behavioursEnabled ? attrs.behavioursEnabled === 'true' : DEFAULT_BEHAVIOURS;
-  let snippetsEnabled = attrs.snippetsEnabled ? attrs.snippetsEnabled === 'true' : DEFAULT_SNIPPETS;
+  const langMode = attrs.mode || DEFAULT_MODE;
+  const maxLines = attrs.maxLines || DEFAULT_MAX_LINES;
+  const showGutter = attrs.showGutter !== undefined;
+  const tabSize = attrs.tabSize || DEFAULT_TAB_SIZE;
+  const behavioursEnabled = attrs.behavioursEnabled ? attrs.behavioursEnabled === 'true' : DEFAULT_BEHAVIOURS;
+  const snippetsEnabled = attrs.snippetsEnabled ? attrs.snippetsEnabled === 'true' : DEFAULT_SNIPPETS;
 
   // Initialize editor
-  let aceElem = elem.get(0);
-  let codeEditor = ace.edit(aceElem);
-  let editorSession = codeEditor.getSession();
+  const aceElem = elem.get(0);
+  const codeEditor = ace.edit(aceElem);
+  const editorSession = codeEditor.getSession();
 
-  let editorOptions = {
+  const editorOptions = {
     maxLines: maxLines,
     showGutter: showGutter,
     tabSize: tabSize,
@@ -93,7 +93,7 @@ function link(scope, elem, attrs) {
 
   // Add classes
   elem.addClass('gf-code-editor');
-  let textarea = elem.find('textarea');
+  const textarea = elem.find('textarea');
   textarea.addClass('gf-form-input');
 
   if (scope.codeEditorFocus) {
@@ -110,14 +110,14 @@ function link(scope, elem, attrs) {
   // Event handlers
   editorSession.on('change', e => {
     scope.$apply(() => {
-      let newValue = codeEditor.getValue();
+      const newValue = codeEditor.getValue();
       scope.content = newValue;
     });
   });
 
   // Sync with outer scope - update editor content if model has been changed from outside of directive.
   scope.$watch('content', (newValue, oldValue) => {
-    let editorValue = codeEditor.getValue();
+    const editorValue = codeEditor.getValue();
     if (newValue !== editorValue && newValue !== oldValue) {
       scope.$$postDigest(function() {
         setEditorContent(newValue);
@@ -157,7 +157,7 @@ function link(scope, elem, attrs) {
       anyEditor.completers.push(scope.getCompleter());
     }
 
-    let aceModeName = `ace/mode/${lang}`;
+    const aceModeName = `ace/mode/${lang}`;
     editorSession.setMode(aceModeName);
   }
 
diff --git a/public/app/core/components/colorpicker/ColorPicker.tsx b/public/app/core/components/colorpicker/ColorPicker.tsx
index c492d3829ca..6e5083b6d6b 100644
--- a/public/app/core/components/colorpicker/ColorPicker.tsx
+++ b/public/app/core/components/colorpicker/ColorPicker.tsx
@@ -29,10 +29,10 @@ export class ColorPicker extends React.Component<Props, any> {
   openColorPicker() {
     const dropContent = <ColorPickerPopover color={this.props.color} onColorSelect={this.onColorSelect} />;
 
-    let dropContentElem = document.createElement('div');
+    const dropContentElem = document.createElement('div');
     ReactDOM.render(dropContent, dropContentElem);
 
-    let drop = new Drop({
+    const drop = new Drop({
       target: this.pickerElem[0],
       content: dropContentElem,
       position: 'top center',
diff --git a/public/app/core/components/colorpicker/ColorPickerPopover.tsx b/public/app/core/components/colorpicker/ColorPickerPopover.tsx
index ac7dd6a2738..c42bcfa1d06 100644
--- a/public/app/core/components/colorpicker/ColorPickerPopover.tsx
+++ b/public/app/core/components/colorpicker/ColorPickerPopover.tsx
@@ -28,7 +28,7 @@ export class ColorPickerPopover extends React.Component<Props, any> {
   }
 
   setColor(color) {
-    let newColor = tinycolor(color);
+    const newColor = tinycolor(color);
     if (newColor.isValid()) {
       this.setState({
         color: newColor.toString(),
@@ -43,20 +43,20 @@ export class ColorPickerPopover extends React.Component<Props, any> {
   }
 
   spectrumColorSelected(color) {
-    let rgbColor = color.toRgbString();
+    const rgbColor = color.toRgbString();
     this.setColor(rgbColor);
   }
 
   onColorStringChange(e) {
-    let colorString = e.target.value;
+    const colorString = e.target.value;
     this.setState({
       colorString: colorString,
     });
 
-    let newColor = tinycolor(colorString);
+    const newColor = tinycolor(colorString);
     if (newColor.isValid()) {
       // Update only color state
-      let newColorString = newColor.toString();
+      const newColorString = newColor.toString();
       this.setState({
         color: newColorString,
       });
@@ -65,7 +65,7 @@ export class ColorPickerPopover extends React.Component<Props, any> {
   }
 
   onColorStringBlur(e) {
-    let colorString = e.target.value;
+    const colorString = e.target.value;
     this.setColor(colorString);
   }
 
@@ -73,7 +73,7 @@ export class ColorPickerPopover extends React.Component<Props, any> {
     this.pickerNavElem.find('li:first').addClass('active');
     this.pickerNavElem.on('show', e => {
       // use href attr (#name => name)
-      let tab = e.target.hash.slice(1);
+      const tab = e.target.hash.slice(1);
       this.setState({
         tab: tab,
       });
diff --git a/public/app/core/components/colorpicker/SpectrumPicker.tsx b/public/app/core/components/colorpicker/SpectrumPicker.tsx
index e8a30e8c460..15a76068e9b 100644
--- a/public/app/core/components/colorpicker/SpectrumPicker.tsx
+++ b/public/app/core/components/colorpicker/SpectrumPicker.tsx
@@ -29,7 +29,7 @@ export class SpectrumPicker extends React.Component<Props, any> {
   }
 
   componentDidMount() {
-    let spectrumOptions = _.assignIn(
+    const spectrumOptions = _.assignIn(
       {
         flat: true,
         showAlpha: true,
diff --git a/public/app/core/components/form_dropdown/form_dropdown.ts b/public/app/core/components/form_dropdown/form_dropdown.ts
index 7ac55e54cf1..007c7c3acb1 100644
--- a/public/app/core/components/form_dropdown/form_dropdown.ts
+++ b/public/app/core/components/form_dropdown/form_dropdown.ts
@@ -132,7 +132,7 @@ export class FormDropdownCtrl {
       this.optionCache = options;
 
       // extract texts
-      let optionTexts = _.map(options, op => {
+      const optionTexts = _.map(options, op => {
         return _.escape(op.text);
       });
 
diff --git a/public/app/core/components/grafana_app.ts b/public/app/core/components/grafana_app.ts
index bd6b6975006..1f55bc332ac 100644
--- a/public/app/core/components/grafana_app.ts
+++ b/public/app/core/components/grafana_app.ts
@@ -140,7 +140,7 @@ export function grafanaAppDirective(playlistSrv, contextSrv, $timeout, $rootScop
         }
 
         // close all drops
-        for (let drop of Drop.drops) {
+        for (const drop of Drop.drops) {
           drop.destroy();
         }
       });
diff --git a/public/app/core/components/info_popover.ts b/public/app/core/components/info_popover.ts
index 59332a6f716..ae4feeec701 100644
--- a/public/app/core/components/info_popover.ts
+++ b/public/app/core/components/info_popover.ts
@@ -8,10 +8,10 @@ export function infoPopover() {
     template: '<i class="fa fa-info-circle"></i>',
     transclude: true,
     link: function(scope, elem, attrs, ctrl, transclude) {
-      let offset = attrs.offset || '0 -10px';
-      let position = attrs.position || 'right middle';
+      const offset = attrs.offset || '0 -10px';
+      const position = attrs.position || 'right middle';
       let classes = 'drop-help drop-hide-out-of-bounds';
-      let openOn = 'hover';
+      const openOn = 'hover';
 
       elem.addClass('gf-form-help-icon');
 
@@ -24,14 +24,14 @@ export function infoPopover() {
       }
 
       transclude(function(clone, newScope) {
-        let content = document.createElement('div');
+        const content = document.createElement('div');
         content.className = 'markdown-html';
 
         _.each(clone, node => {
           content.appendChild(node);
         });
 
-        let dropOptions = {
+        const dropOptions = {
           target: elem[0],
           content: content,
           position: position,
@@ -52,9 +52,9 @@ export function infoPopover() {
 
         // Create drop in next digest after directive content is rendered.
         scope.$applyAsync(() => {
-          let drop = new Drop(dropOptions);
+          const drop = new Drop(dropOptions);
 
-          let unbind = scope.$on('$destroy', function() {
+          const unbind = scope.$on('$destroy', function() {
             drop.destroy();
             unbind();
           });
diff --git a/public/app/core/components/manage_dashboards/manage_dashboards.ts b/public/app/core/components/manage_dashboards/manage_dashboards.ts
index 86cd3066c48..59a34d08c12 100644
--- a/public/app/core/components/manage_dashboards/manage_dashboards.ts
+++ b/public/app/core/components/manage_dashboards/manage_dashboards.ts
@@ -103,10 +103,10 @@ export class ManageDashboardsCtrl {
 
     this.sections = result;
 
-    for (let section of this.sections) {
+    for (const section of this.sections) {
       section.checked = false;
 
-      for (let dashboard of section.items) {
+      for (const dashboard of section.items) {
         dashboard.checked = false;
       }
     }
@@ -119,7 +119,7 @@ export class ManageDashboardsCtrl {
   selectionChanged() {
     let selectedDashboards = 0;
 
-    for (let section of this.sections) {
+    for (const section of this.sections) {
       selectedDashboards += _.filter(section.items, { checked: true }).length;
     }
 
@@ -129,7 +129,7 @@ export class ManageDashboardsCtrl {
   }
 
   getFoldersAndDashboardsToDelete() {
-    let selectedDashboards = {
+    const selectedDashboards = {
       folders: [],
       dashboards: [],
     };
@@ -148,7 +148,7 @@ export class ManageDashboardsCtrl {
 
   getFolderIds(sections) {
     const ids = [];
-    for (let s of sections) {
+    for (const s of sections) {
       if (s.checked) {
         ids.push(s.id);
       }
@@ -191,7 +191,7 @@ export class ManageDashboardsCtrl {
   }
 
   getDashboardsToMove() {
-    let selectedDashboards = [];
+    const selectedDashboards = [];
 
     for (const section of this.sections) {
       const selected = _.filter(section.items, { checked: true });
@@ -264,7 +264,7 @@ export class ManageDashboardsCtrl {
   }
 
   onSelectAllChanged() {
-    for (let section of this.sections) {
+    for (const section of this.sections) {
       if (!section.hideHeader) {
         section.checked = this.selectAllChecked;
       }
diff --git a/public/app/core/components/scroll/scroll.ts b/public/app/core/components/scroll/scroll.ts
index 3f9865e6dce..5cdbdb62ee3 100644
--- a/public/app/core/components/scroll/scroll.ts
+++ b/public/app/core/components/scroll/scroll.ts
@@ -17,7 +17,7 @@ export function geminiScrollbar() {
     restrict: 'A',
     link: function(scope, elem, attrs) {
       let scrollRoot = elem.parent();
-      let scroller = elem;
+      const scroller = elem;
 
       if (attrs.grafanaScrollbar && attrs.grafanaScrollbar === 'scrollonroot') {
         scrollRoot = scroller;
@@ -27,7 +27,7 @@ export function geminiScrollbar() {
       $(scrollBarHTML).appendTo(scrollRoot);
       elem.addClass(scrollerClass);
 
-      let scrollParams = {
+      const scrollParams = {
         root: scrollRoot[0],
         scroller: scroller[0],
         bar: '.baron__bar',
@@ -37,7 +37,7 @@ export function geminiScrollbar() {
         direction: 'v',
       };
 
-      let scrollbar = baron(scrollParams);
+      const scrollbar = baron(scrollParams);
 
       let lastPos = 0;
 
diff --git a/public/app/core/components/search/SearchResult.tsx b/public/app/core/components/search/SearchResult.tsx
index 5ab4bba8edb..3141d29ac7f 100644
--- a/public/app/core/components/search/SearchResult.tsx
+++ b/public/app/core/components/search/SearchResult.tsx
@@ -54,7 +54,7 @@ export class SearchResultSection extends React.Component<SectionProps, any> {
   };
 
   render() {
-    let collapseClassNames = classNames({
+    const collapseClassNames = classNames({
       fa: true,
       'fa-plus': !this.props.section.expanded,
       'fa-minus': this.props.section.expanded,
diff --git a/public/app/core/components/sidemenu/sidemenu.ts b/public/app/core/components/sidemenu/sidemenu.ts
index fb9d9be7f70..5649963c3dc 100644
--- a/public/app/core/components/sidemenu/sidemenu.ts
+++ b/public/app/core/components/sidemenu/sidemenu.ts
@@ -17,13 +17,13 @@ export class SideMenuCtrl {
     this.isSignedIn = contextSrv.isSignedIn;
     this.user = contextSrv.user;
 
-    let navTree = _.cloneDeep(config.bootData.navTree);
+    const navTree = _.cloneDeep(config.bootData.navTree);
     this.mainLinks = _.filter(navTree, item => !item.hideFromMenu);
     this.bottomNav = _.filter(navTree, item => item.hideFromMenu);
     this.loginUrl = 'login?redirect=' + encodeURIComponent(this.$location.path());
 
     if (contextSrv.user.orgCount > 1) {
-      let profileNode = _.find(this.bottomNav, { id: 'profile' });
+      const profileNode = _.find(this.bottomNav, { id: 'profile' });
       if (profileNode) {
         profileNode.showOrgSwitcher = true;
       }
diff --git a/public/app/core/controllers/login_ctrl.ts b/public/app/core/controllers/login_ctrl.ts
index 0a66f83d08a..6662686b238 100644
--- a/public/app/core/controllers/login_ctrl.ts
+++ b/public/app/core/controllers/login_ctrl.ts
@@ -45,8 +45,8 @@ export class LoginCtrl {
     };
 
     $scope.changeView = function() {
-      let loginView = document.querySelector('#login-view');
-      let changePasswordView = document.querySelector('#change-password-view');
+      const loginView = document.querySelector('#login-view');
+      const changePasswordView = document.querySelector('#change-password-view');
 
       loginView.className += ' add';
       setTimeout(() => {
diff --git a/public/app/core/directives/dropdown_typeahead.ts b/public/app/core/directives/dropdown_typeahead.ts
index c9e44c5e786..af8c4ddc3bb 100644
--- a/public/app/core/directives/dropdown_typeahead.ts
+++ b/public/app/core/directives/dropdown_typeahead.ts
@@ -4,12 +4,12 @@ import coreModule from '../core_module';
 
 /** @ngInject */
 export function dropdownTypeahead($compile) {
-  let inputTemplate =
+  const inputTemplate =
     '<input type="text"' +
     ' class="gf-form-input input-medium tight-form-input"' +
     ' spellcheck="false" style="display:none"></input>';
 
-  let buttonTemplate =
+  const buttonTemplate =
     '<a class="gf-form-label tight-form-func dropdown-toggle"' +
     ' tabindex="1" gf-dropdown="menuItems" data-toggle="dropdown"' +
     ' data-placement="top"><i class="fa fa-plus"></i></a>';
@@ -21,8 +21,8 @@ export function dropdownTypeahead($compile) {
       model: '=ngModel',
     },
     link: function($scope, elem, attrs) {
-      let $input = $(inputTemplate);
-      let $button = $(buttonTemplate);
+      const $input = $(inputTemplate);
+      const $button = $(buttonTemplate);
       $input.appendTo(elem);
       $button.appendTo(elem);
 
@@ -42,7 +42,7 @@ export function dropdownTypeahead($compile) {
         });
       }
 
-      let typeaheadValues = _.reduce(
+      const typeaheadValues = _.reduce(
         $scope.menuItems,
         function(memo, value, index) {
           if (!value.submenu) {
@@ -60,8 +60,8 @@ export function dropdownTypeahead($compile) {
       );
 
       $scope.menuItemSelected = function(index, subIndex) {
-        let menuItem = $scope.menuItems[index];
-        let payload: any = { $item: menuItem };
+        const menuItem = $scope.menuItems[index];
+        const payload: any = { $item: menuItem };
         if (menuItem.submenu && subIndex !== void 0) {
           payload.$subItem = menuItem.submenu[subIndex];
         }
@@ -74,7 +74,7 @@ export function dropdownTypeahead($compile) {
         minLength: 1,
         items: 10,
         updater: function(value) {
-          let result: any = {};
+          const result: any = {};
           _.each($scope.menuItems, function(menuItem) {
             _.each(menuItem.submenu, function(submenuItem) {
               if (value === menuItem.text + ' ' + submenuItem.text) {
@@ -124,10 +124,10 @@ export function dropdownTypeahead($compile) {
 
 /** @ngInject */
 export function dropdownTypeahead2($compile) {
-  let inputTemplate =
+  const inputTemplate =
     '<input type="text"' + ' class="gf-form-input"' + ' spellcheck="false" style="display:none"></input>';
 
-  let buttonTemplate =
+  const buttonTemplate =
     '<a class="gf-form-input dropdown-toggle"' +
     ' tabindex="1" gf-dropdown="menuItems" data-toggle="dropdown"' +
     ' data-placement="top"><i class="fa fa-plus"></i></a>';
@@ -139,8 +139,8 @@ export function dropdownTypeahead2($compile) {
       model: '=ngModel',
     },
     link: function($scope, elem, attrs) {
-      let $input = $(inputTemplate);
-      let $button = $(buttonTemplate);
+      const $input = $(inputTemplate);
+      const $button = $(buttonTemplate);
       $input.appendTo(elem);
       $button.appendTo(elem);
 
@@ -160,7 +160,7 @@ export function dropdownTypeahead2($compile) {
         });
       }
 
-      let typeaheadValues = _.reduce(
+      const typeaheadValues = _.reduce(
         $scope.menuItems,
         function(memo, value, index) {
           if (!value.submenu) {
@@ -178,8 +178,8 @@ export function dropdownTypeahead2($compile) {
       );
 
       $scope.menuItemSelected = function(index, subIndex) {
-        let menuItem = $scope.menuItems[index];
-        let payload: any = { $item: menuItem };
+        const menuItem = $scope.menuItems[index];
+        const payload: any = { $item: menuItem };
         if (menuItem.submenu && subIndex !== void 0) {
           payload.$subItem = menuItem.submenu[subIndex];
         }
@@ -192,7 +192,7 @@ export function dropdownTypeahead2($compile) {
         minLength: 1,
         items: 10,
         updater: function(value) {
-          let result: any = {};
+          const result: any = {};
           _.each($scope.menuItems, function(menuItem) {
             _.each(menuItem.submenu, function(submenuItem) {
               if (value === menuItem.text + ' ' + submenuItem.text) {
diff --git a/public/app/core/directives/metric_segment.ts b/public/app/core/directives/metric_segment.ts
index 3718d7fbd4a..117f776f487 100644
--- a/public/app/core/directives/metric_segment.ts
+++ b/public/app/core/directives/metric_segment.ts
@@ -4,16 +4,16 @@ import coreModule from '../core_module';
 
 /** @ngInject */
 export function metricSegment($compile, $sce) {
-  let inputTemplate =
+  const inputTemplate =
     '<input type="text" data-provide="typeahead" ' +
     ' class="gf-form-input input-medium"' +
     ' spellcheck="false" style="display:none"></input>';
 
-  let linkTemplate =
+  const linkTemplate =
     '<a class="gf-form-label" ng-class="segment.cssClass" ' +
     'tabindex="1" give-focus="segment.focus" ng-bind-html="segment.html"></a>';
 
-  let selectTemplate =
+  const selectTemplate =
     '<a class="gf-form-input gf-form-input--dropdown" ng-class="segment.cssClass" ' +
     'tabindex="1" give-focus="segment.focus" ng-bind-html="segment.html"></a>';
 
@@ -25,13 +25,13 @@ export function metricSegment($compile, $sce) {
       debounce: '@',
     },
     link: function($scope, elem) {
-      let $input = $(inputTemplate);
-      let segment = $scope.segment;
-      let $button = $(segment.selectMode ? selectTemplate : linkTemplate);
+      const $input = $(inputTemplate);
+      const segment = $scope.segment;
+      const $button = $(segment.selectMode ? selectTemplate : linkTemplate);
       let options = null;
       let cancelBlur = null;
       let linkMode = true;
-      let debounceLookup = $scope.debounce;
+      const debounceLookup = $scope.debounce;
 
       $input.appendTo(elem);
       $button.appendTo(elem);
@@ -44,7 +44,7 @@ export function metricSegment($compile, $sce) {
         value = _.unescape(value);
 
         $scope.$apply(function() {
-          let selected = _.find($scope.altSegments, { value: value });
+          const selected = _.find($scope.altSegments, { value: value });
           if (selected) {
             segment.value = selected.value;
             segment.html = selected.html || selected.value;
@@ -141,10 +141,10 @@ export function metricSegment($compile, $sce) {
         matcher: $scope.matcher,
       });
 
-      let typeahead = $input.data('typeahead');
+      const typeahead = $input.data('typeahead');
       typeahead.lookup = function() {
         this.query = this.$element.val() || '';
-        let items = this.source(this.query, $.proxy(this.process, this));
+        const items = this.source(this.query, $.proxy(this.process, this));
         return items ? this.process(items) : items;
       };
 
@@ -169,7 +169,7 @@ export function metricSegment($compile, $sce) {
 
         linkMode = false;
 
-        let typeahead = $input.data('typeahead');
+        const typeahead = $input.data('typeahead');
         if (typeahead) {
           $input.val('');
           typeahead.lookup();
@@ -200,8 +200,8 @@ export function metricSegmentModel(uiSegmentSrv, $q) {
         let cachedOptions;
 
         $scope.valueToSegment = function(value) {
-          let option = _.find($scope.options, { value: value });
-          let segment = {
+          const option = _.find($scope.options, { value: value });
+          const segment = {
             cssClass: attrs.cssClass,
             custom: attrs.custom,
             value: option ? option.text : value,
@@ -234,7 +234,7 @@ export function metricSegmentModel(uiSegmentSrv, $q) {
 
         $scope.onSegmentChange = function() {
           if (cachedOptions) {
-            let option = _.find(cachedOptions, { text: $scope.segment.value });
+            const option = _.find(cachedOptions, { text: $scope.segment.value });
             if (option && option.value !== $scope.property) {
               $scope.property = option.value;
             } else if (attrs.custom !== 'false') {
diff --git a/public/app/core/directives/misc.ts b/public/app/core/directives/misc.ts
index 299de05f112..034b312aa0e 100644
--- a/public/app/core/directives/misc.ts
+++ b/public/app/core/directives/misc.ts
@@ -156,7 +156,7 @@ function gfDropdown($parse, $compile, $timeout) {
     var ul = ['<ul class="dropdown-menu ' + upclass + '" role="menu" aria-labelledby="drop1">', '</ul>'];
 
     for (let index = 0; index < items.length; index++) {
-      let item = items[index];
+      const item = items[index];
 
       if (item.divider) {
         ul.splice(index + 1, 0, '<li class="divider"></li>');
diff --git a/public/app/core/directives/value_select_dropdown.ts b/public/app/core/directives/value_select_dropdown.ts
index d384904c2d8..69504c1bb1b 100644
--- a/public/app/core/directives/value_select_dropdown.ts
+++ b/public/app/core/directives/value_select_dropdown.ts
@@ -46,16 +46,16 @@ export class ValueSelectDropdownCtrl {
   }
 
   updateLinkText() {
-    let current = this.variable.current;
+    const current = this.variable.current;
 
     if (current.tags && current.tags.length) {
       // filer out values that are in selected tags
-      let selectedAndNotInTag = _.filter(this.variable.options, option => {
+      const selectedAndNotInTag = _.filter(this.variable.options, option => {
         if (!option.selected) {
           return false;
         }
         for (let i = 0; i < current.tags.length; i++) {
-          let tag = current.tags[i];
+          const tag = current.tags[i];
           if (_.indexOf(tag.values, option.value) !== -1) {
             return false;
           }
@@ -64,7 +64,7 @@ export class ValueSelectDropdownCtrl {
       });
 
       // convert values to text
-      let currentTexts = _.map(selectedAndNotInTag, 'text');
+      const currentTexts = _.map(selectedAndNotInTag, 'text');
 
       // join texts
       this.linkText = currentTexts.join(' + ');
@@ -142,7 +142,7 @@ export class ValueSelectDropdownCtrl {
     commitChange = commitChange || false;
     excludeOthers = excludeOthers || false;
 
-    let setAllExceptCurrentTo = newValue => {
+    const setAllExceptCurrentTo = newValue => {
       _.each(this.options, other => {
         if (option !== other) {
           other.selected = newValue;
@@ -246,9 +246,9 @@ export function valueSelectDropdown($compile, $window, $timeout, $rootScope) {
     controllerAs: 'vm',
     bindToController: true,
     link: function(scope, elem) {
-      let bodyEl = angular.element($window.document.body);
-      let linkEl = elem.find('.variable-value-link');
-      let inputEl = elem.find('input');
+      const bodyEl = angular.element($window.document.body);
+      const linkEl = elem.find('.variable-value-link');
+      const inputEl = elem.find('input');
 
       function openDropdown() {
         inputEl.css('width', Math.max(linkEl.width(), 80) + 'px');
@@ -288,7 +288,7 @@ export function valueSelectDropdown($compile, $window, $timeout, $rootScope) {
         }
       });
 
-      let cleanUp = $rootScope.$on('template-variable-value-updated', () => {
+      const cleanUp = $rootScope.$on('template-variable-value-updated', () => {
         scope.vm.updateLinkText();
       });
 
diff --git a/public/app/core/nav_model_srv.ts b/public/app/core/nav_model_srv.ts
index a9ebd4e79ed..2bed33e70da 100644
--- a/public/app/core/nav_model_srv.ts
+++ b/public/app/core/nav_model_srv.ts
@@ -41,14 +41,14 @@ export class NavModelSrv {
     var children = this.navItems;
     var nav = new NavModel();
 
-    for (let id of args) {
+    for (const id of args) {
       // if its a number then it's the index to use for main
       if (_.isNumber(id)) {
         nav.main = nav.breadcrumbs[id];
         break;
       }
 
-      let node = _.find(children, { id: id });
+      const node = _.find(children, { id: id });
       nav.breadcrumbs.push(node);
       nav.node = node;
       nav.main = node;
@@ -56,7 +56,7 @@ export class NavModelSrv {
     }
 
     if (nav.main.children) {
-      for (let item of nav.main.children) {
+      for (const item of nav.main.children) {
         item.active = false;
 
         if (item.url === nav.node.url) {
diff --git a/public/app/core/services/backend_srv.ts b/public/app/core/services/backend_srv.ts
index 1aeeedef4dd..4dd8a123378 100644
--- a/public/app/core/services/backend_srv.ts
+++ b/public/app/core/services/backend_srv.ts
@@ -276,11 +276,11 @@ export class BackendSrv {
   deleteFoldersAndDashboards(folderUids, dashboardUids) {
     const tasks = [];
 
-    for (let folderUid of folderUids) {
+    for (const folderUid of folderUids) {
       tasks.push(this.createTask(this.deleteFolder.bind(this), true, folderUid, true));
     }
 
-    for (let dashboardUid of dashboardUids) {
+    for (const dashboardUid of dashboardUids) {
       tasks.push(this.createTask(this.deleteDashboard.bind(this), true, dashboardUid, true));
     }
 
@@ -290,7 +290,7 @@ export class BackendSrv {
   moveDashboards(dashboardUids, toFolder) {
     const tasks = [];
 
-    for (let uid of dashboardUids) {
+    for (const uid of dashboardUids) {
       tasks.push(this.createTask(this.moveDashboard.bind(this), true, uid, toFolder));
     }
 
@@ -304,7 +304,7 @@ export class BackendSrv {
   }
 
   private moveDashboard(uid, toFolder) {
-    let deferred = this.$q.defer();
+    const deferred = this.$q.defer();
 
     this.getDashboardByUid(uid).then(fullDash => {
       const model = new DashboardModel(fullDash.dashboard, fullDash.meta);
@@ -315,7 +315,7 @@ export class BackendSrv {
       }
 
       const clone = model.getSaveModelClone();
-      let options = {
+      const options = {
         folderId: toFolder.id,
         overwrite: false,
       };
diff --git a/public/app/core/services/bridge_srv.ts b/public/app/core/services/bridge_srv.ts
index 4a5649a6c52..bdc2976a94c 100644
--- a/public/app/core/services/bridge_srv.ts
+++ b/public/app/core/services/bridge_srv.ts
@@ -15,7 +15,7 @@ export class BridgeSrv {
 
   init() {
     this.$rootScope.$on('$routeUpdate', (evt, data) => {
-      let angularUrl = this.$location.url();
+      const angularUrl = this.$location.url();
       if (store.view.currentUrl !== angularUrl) {
         store.view.updatePathAndQuery(this.$location.path(), this.$location.search(), this.$route.current.params);
       }
@@ -28,7 +28,7 @@ export class BridgeSrv {
     reaction(
       () => store.view.currentUrl,
       currentUrl => {
-        let angularUrl = this.$location.url();
+        const angularUrl = this.$location.url();
         const url = locationUtil.stripBaseFromUrl(currentUrl);
         if (angularUrl !== url) {
           this.$timeout(() => {
diff --git a/public/app/core/services/dynamic_directive_srv.ts b/public/app/core/services/dynamic_directive_srv.ts
index 086843b6f9a..de06daf2c1a 100644
--- a/public/app/core/services/dynamic_directive_srv.ts
+++ b/public/app/core/services/dynamic_directive_srv.ts
@@ -36,7 +36,7 @@ class DynamicDirectiveSrv {
   }
 
   create(options) {
-    let directiveDef = {
+    const directiveDef = {
       restrict: 'E',
       scope: options.scope,
       link: (scope, elem, attrs) => {
diff --git a/public/app/core/services/keybindingSrv.ts b/public/app/core/services/keybindingSrv.ts
index 9d914a94a1c..5405a347ba0 100644
--- a/public/app/core/services/keybindingSrv.ts
+++ b/public/app/core/services/keybindingSrv.ts
@@ -210,7 +210,7 @@ export class KeybindingSrv {
     // duplicate panel
     this.bind('p d', () => {
       if (dashboard.meta.focusPanelId && dashboard.meta.canEdit) {
-        let panelIndex = dashboard.getPanelInfoById(dashboard.meta.focusPanelId).index;
+        const panelIndex = dashboard.getPanelInfoById(dashboard.meta.focusPanelId).index;
         dashboard.duplicatePanel(dashboard.panels[panelIndex]);
       }
     });
diff --git a/public/app/core/services/ng_react.ts b/public/app/core/services/ng_react.ts
index 3c61412669e..aeffaaa9b3b 100644
--- a/public/app/core/services/ng_react.ts
+++ b/public/app/core/services/ng_react.ts
@@ -295,6 +295,6 @@ var reactDirective = function($injector) {
   };
 };
 
-let ngModule = angular.module('react', []);
+const ngModule = angular.module('react', []);
 ngModule.directive('reactComponent', ['$injector', reactComponent]);
 ngModule.factory('reactDirective', ['$injector', reactDirective]);
diff --git a/public/app/core/services/search_srv.ts b/public/app/core/services/search_srv.ts
index 9f32e21f3f6..017b2c15efc 100644
--- a/public/app/core/services/search_srv.ts
+++ b/public/app/core/services/search_srv.ts
@@ -85,10 +85,10 @@ export class SearchSrv {
   }
 
   search(options) {
-    let sections: any = {};
-    let promises = [];
-    let query = _.clone(options);
-    let hasFilters =
+    const sections: any = {};
+    const promises = [];
+    const query = _.clone(options);
+    const hasFilters =
       options.query ||
       (options.tag && options.tag.length > 0) ||
       options.starred ||
@@ -124,7 +124,7 @@ export class SearchSrv {
     }
 
     // create folder index
-    for (let hit of results) {
+    for (const hit of results) {
       if (hit.type === 'dash-folder') {
         sections[hit.id] = {
           id: hit.id,
@@ -140,7 +140,7 @@ export class SearchSrv {
       }
     }
 
-    for (let hit of results) {
+    for (const hit of results) {
       if (hit.type === 'dash-folder') {
         continue;
       }
@@ -185,7 +185,7 @@ export class SearchSrv {
       return Promise.resolve(section);
     }
 
-    let query = {
+    const query = {
       folderIds: [section.id],
     };
 
diff --git a/public/app/core/services/segment_srv.ts b/public/app/core/services/segment_srv.ts
index 042340e6102..5250febc11a 100644
--- a/public/app/core/services/segment_srv.ts
+++ b/public/app/core/services/segment_srv.ts
@@ -3,7 +3,7 @@ import coreModule from '../core_module';
 
 /** @ngInject */
 export function uiSegmentSrv($sce, templateSrv) {
-  let self = this;
+  const self = this;
 
   function MetricSegment(options) {
     if (options === '*' || options.value === '*') {
@@ -78,7 +78,7 @@ export function uiSegmentSrv($sce, templateSrv) {
 
   this.transformToSegments = function(addTemplateVars, variableTypeFilter) {
     return function(results) {
-      let segments = _.map(results, function(segment) {
+      const segments = _.map(results, function(segment) {
         return self.newSegment({ value: segment.text, expandable: segment.expandable });
       });
 
diff --git a/public/app/core/specs/backend_srv.test.ts b/public/app/core/specs/backend_srv.test.ts
index b19bd117766..e9cd5973d36 100644
--- a/public/app/core/specs/backend_srv.test.ts
+++ b/public/app/core/specs/backend_srv.test.ts
@@ -2,14 +2,14 @@ import { BackendSrv } from 'app/core/services/backend_srv';
 jest.mock('app/core/store');
 
 describe('backend_srv', function() {
-  let _httpBackend = options => {
+  const _httpBackend = options => {
     if (options.url === 'gateway-error') {
       return Promise.reject({ status: 502 });
     }
     return Promise.resolve({});
   };
 
-  let _backendSrv = new BackendSrv(_httpBackend, {}, {}, {}, {});
+  const _backendSrv = new BackendSrv(_httpBackend, {}, {}, {}, {});
 
   describe('when handling errors', () => {
     it('should return the http status code', async () => {
diff --git a/public/app/core/specs/file_export.test.ts b/public/app/core/specs/file_export.test.ts
index 915ce08fcd2..ced94fcdbc0 100644
--- a/public/app/core/specs/file_export.test.ts
+++ b/public/app/core/specs/file_export.test.ts
@@ -2,7 +2,7 @@ import * as fileExport from '../utils/file_export';
 import { beforeEach, expect } from 'test/lib/common';
 
 describe('file_export', () => {
-  let ctx: any = {};
+  const ctx: any = {};
 
   beforeEach(() => {
     ctx.seriesList = [
@@ -28,7 +28,7 @@ describe('file_export', () => {
 
   describe('when exporting series as rows', () => {
     it('should export points in proper order', () => {
-      let text = fileExport.convertSeriesListToCsv(ctx.seriesList, ctx.timeFormat);
+      const text = fileExport.convertSeriesListToCsv(ctx.seriesList, ctx.timeFormat);
       const expectedText =
         '"Series";"Time";"Value"\r\n' +
         '"series_1";"1500026100";1\r\n' +
@@ -48,7 +48,7 @@ describe('file_export', () => {
 
   describe('when exporting series as columns', () => {
     it('should export points in proper order', () => {
-      let text = fileExport.convertSeriesListToCsvColumns(ctx.seriesList, ctx.timeFormat);
+      const text = fileExport.convertSeriesListToCsvColumns(ctx.seriesList, ctx.timeFormat);
       const expectedText =
         '"Time";"series_1";"series_2"\r\n' +
         '"1500026100";1;11\r\n' +
diff --git a/public/app/core/specs/search.test.ts b/public/app/core/specs/search.test.ts
index 8aea35af213..3cc789b3cc5 100644
--- a/public/app/core/specs/search.test.ts
+++ b/public/app/core/specs/search.test.ts
@@ -12,7 +12,7 @@ describe('SearchCtrl', () => {
     search: (options: any) => {},
     getDashboardTags: () => {},
   };
-  let ctrl = new SearchCtrl({ $on: () => {} }, {}, {}, <SearchSrv>searchSrvStub);
+  const ctrl = new SearchCtrl({ $on: () => {} }, {}, {}, <SearchSrv>searchSrvStub);
 
   describe('Given an empty result', () => {
     beforeEach(() => {
diff --git a/public/app/core/specs/search_results.test.ts b/public/app/core/specs/search_results.test.ts
index 830496be3a8..96dbc8bb963 100644
--- a/public/app/core/specs/search_results.test.ts
+++ b/public/app/core/specs/search_results.test.ts
@@ -12,7 +12,7 @@ describe('SearchResultsCtrl', () => {
   let ctrl;
 
   describe('when checking an item that is not checked', () => {
-    let item = { checked: false };
+    const item = { checked: false };
     let selectionChanged = false;
 
     beforeEach(() => {
@@ -31,7 +31,7 @@ describe('SearchResultsCtrl', () => {
   });
 
   describe('when checking an item that is checked', () => {
-    let item = { checked: true };
+    const item = { checked: true };
     let selectionChanged = false;
 
     beforeEach(() => {
@@ -72,7 +72,7 @@ describe('SearchResultsCtrl', () => {
         folderExpanded = true;
       };
 
-      let folder = {
+      const folder = {
         expanded: false,
         toggle: () => Promise.resolve(folder),
       };
@@ -94,7 +94,7 @@ describe('SearchResultsCtrl', () => {
         folderExpanded = true;
       };
 
-      let folder = {
+      const folder = {
         expanded: true,
         toggle: () => Promise.resolve(folder),
       };
diff --git a/public/app/core/specs/ticks.test.ts b/public/app/core/specs/ticks.test.ts
index 8b7e0cd73b5..73d0e96cbd2 100644
--- a/public/app/core/specs/ticks.test.ts
+++ b/public/app/core/specs/ticks.test.ts
@@ -2,7 +2,7 @@ import * as ticks from '../utils/ticks';
 
 describe('ticks', () => {
   describe('getFlotTickDecimals()', () => {
-    let ctx: any = {};
+    const ctx: any = {};
 
     beforeEach(() => {
       ctx.axis = {};
diff --git a/public/app/core/specs/time_series.test.ts b/public/app/core/specs/time_series.test.ts
index bf50d807e03..35b75b3da5e 100644
--- a/public/app/core/specs/time_series.test.ts
+++ b/public/app/core/specs/time_series.test.ts
@@ -329,7 +329,7 @@ describe('TimeSeries', function() {
 
   describe('legend decimals', function() {
     let series, panel;
-    let height = 200;
+    const height = 200;
     beforeEach(function() {
       testData = {
         alias: 'test',
@@ -348,7 +348,7 @@ describe('TimeSeries', function() {
     });
 
     it('should set decimals based on Y axis (expect calculated decimals = 1)', function() {
-      let data = [series];
+      const data = [series];
       // Expect ticks with this data will have decimals = 1
       updateLegendValues(data, panel, height);
       expect(data[0].decimals).toBe(2);
@@ -358,21 +358,21 @@ describe('TimeSeries', function() {
       testData.datapoints = [[10, 2], [0, 3], [100, 4], [80, 5]];
       series = new TimeSeries(testData);
       series.getFlotPairs();
-      let data = [series];
+      const data = [series];
       updateLegendValues(data, panel, height);
       expect(data[0].decimals).toBe(0);
     });
 
     it('should set decimals to Y axis decimals + 1', function() {
       panel.yaxes[0].decimals = 2;
-      let data = [series];
+      const data = [series];
       updateLegendValues(data, panel, height);
       expect(data[0].decimals).toBe(3);
     });
 
     it('should set decimals to legend decimals value if it was set explicitly', function() {
       panel.decimals = 3;
-      let data = [series];
+      const data = [series];
       updateLegendValues(data, panel, height);
       expect(data[0].decimals).toBe(3);
     });
diff --git a/public/app/core/specs/value_select_dropdown.test.ts b/public/app/core/specs/value_select_dropdown.test.ts
index 3cc310435b7..024774250b8 100644
--- a/public/app/core/specs/value_select_dropdown.test.ts
+++ b/public/app/core/specs/value_select_dropdown.test.ts
@@ -3,7 +3,7 @@ import { ValueSelectDropdownCtrl } from '../directives/value_select_dropdown';
 import q from 'q';
 
 describe('SelectDropdownCtrl', () => {
-  let tagValuesMap: any = {};
+  const tagValuesMap: any = {};
 
   ValueSelectDropdownCtrl.prototype.onUpdated = jest.fn();
   let ctrl;
diff --git a/public/app/core/time_series2.ts b/public/app/core/time_series2.ts
index f4d0943d52f..c29242c9aca 100644
--- a/public/app/core/time_series2.ts
+++ b/public/app/core/time_series2.ts
@@ -27,11 +27,11 @@ function translateFillOption(fill) {
  */
 export function updateLegendValues(data: TimeSeries[], panel, height) {
   for (let i = 0; i < data.length; i++) {
-    let series = data[i];
+    const series = data[i];
     const yaxes = panel.yaxes;
     const seriesYAxis = series.yaxis || 1;
     const axis = yaxes[seriesYAxis - 1];
-    let formater = kbn.valueFormats[axis.format];
+    const formater = kbn.valueFormats[axis.format];
 
     // decimal override
     if (_.isNumber(panel.decimals)) {
@@ -54,7 +54,7 @@ export function getDataMinMax(data: TimeSeries[]) {
   let datamin = null;
   let datamax = null;
 
-  for (let series of data) {
+  for (const series of data) {
     if (datamax === null || datamax < series.stats.max) {
       datamax = series.stats.max;
     }
@@ -225,7 +225,7 @@ export default class TimeSeries {
       // Due to missing values we could have different timeStep all along the series
       // so we have to find the minimum one (could occur with aggregators such as ZimSum)
       if (previousTime !== undefined) {
-        let timeStep = currentTime - previousTime;
+        const timeStep = currentTime - previousTime;
         if (timeStep < this.stats.timeStep) {
           this.stats.timeStep = timeStep;
         }
diff --git a/public/app/core/utils/colors.ts b/public/app/core/utils/colors.ts
index 8a70e093ea2..e8a7366beb5 100644
--- a/public/app/core/utils/colors.ts
+++ b/public/app/core/utils/colors.ts
@@ -9,7 +9,7 @@ export const ALERTING_COLOR = 'rgba(237, 46, 24, 1)';
 export const NO_DATA_COLOR = 'rgba(150, 150, 150, 1)';
 export const REGION_FILL_ALPHA = 0.09;
 
-let colors = [
+const colors = [
   '#7EB26D',
   '#EAB839',
   '#6ED0E0',
@@ -69,7 +69,7 @@ let colors = [
 ];
 
 export function sortColorsByHue(hexColors) {
-  let hslColors = _.map(hexColors, hexToHsl);
+  const hslColors = _.map(hexColors, hexToHsl);
 
   let sortedHSLColors = _.sortBy(hslColors, ['h']);
   sortedHSLColors = _.chunk(sortedHSLColors, PALETTE_ROWS);
diff --git a/public/app/core/utils/dag.test.ts b/public/app/core/utils/dag.test.ts
index a89ab27cda3..064da13806b 100644
--- a/public/app/core/utils/dag.test.ts
+++ b/public/app/core/utils/dag.test.ts
@@ -2,16 +2,16 @@ import { Graph } from './dag';
 
 describe('Directed acyclic graph', () => {
   describe('Given a graph with nodes with different links in between them', () => {
-    let dag = new Graph();
-    let nodeA = dag.createNode('A');
-    let nodeB = dag.createNode('B');
-    let nodeC = dag.createNode('C');
-    let nodeD = dag.createNode('D');
-    let nodeE = dag.createNode('E');
-    let nodeF = dag.createNode('F');
-    let nodeG = dag.createNode('G');
-    let nodeH = dag.createNode('H');
-    let nodeI = dag.createNode('I');
+    const dag = new Graph();
+    const nodeA = dag.createNode('A');
+    const nodeB = dag.createNode('B');
+    const nodeC = dag.createNode('C');
+    const nodeD = dag.createNode('D');
+    const nodeE = dag.createNode('E');
+    const nodeF = dag.createNode('F');
+    const nodeG = dag.createNode('G');
+    const nodeH = dag.createNode('H');
+    const nodeI = dag.createNode('I');
     dag.link([nodeB, nodeC, nodeD, nodeE, nodeF, nodeG, nodeH], nodeA);
     dag.link([nodeC, nodeD, nodeE, nodeF, nodeI], nodeB);
     dag.link([nodeD, nodeE, nodeF, nodeG], nodeC);
diff --git a/public/app/core/utils/dag.ts b/public/app/core/utils/dag.ts
index 1d61280fb05..eb7ff1c3b1a 100644
--- a/public/app/core/utils/dag.ts
+++ b/public/app/core/utils/dag.ts
@@ -26,8 +26,8 @@ export class Edge {
 
   unlink() {
     let pos;
-    let inode = this.inputNode;
-    let onode = this.outputNode;
+    const inode = this.inputNode;
+    const onode = this.outputNode;
 
     if (!(inode && onode)) {
       return;
@@ -96,12 +96,12 @@ export class Node {
   }
 
   getOptimizedInputEdges(): Edge[] {
-    let toBeRemoved = [];
+    const toBeRemoved = [];
     this.inputEdges.forEach(e => {
-      let inputEdgesNodes = e.inputNode.inputEdges.map(e => e.inputNode);
+      const inputEdgesNodes = e.inputNode.inputEdges.map(e => e.inputNode);
 
       inputEdgesNodes.forEach(n => {
-        let edgeToRemove = n.getEdgeTo(this.name);
+        const edgeToRemove = n.getEdgeTo(this.name);
         if (edgeToRemove) {
           toBeRemoved.push(edgeToRemove);
         }
@@ -124,7 +124,7 @@ export class Graph {
   }
 
   createNodes(names: string[]): Node[] {
-    let nodes = [];
+    const nodes = [];
     names.forEach(name => {
       nodes.push(this.createNode(name));
     });
@@ -134,8 +134,8 @@ export class Graph {
   link(input: string | string[] | Node | Node[], output: string | string[] | Node | Node[]): Edge[] {
     let inputArr = [];
     let outputArr = [];
-    let inputNodes = [];
-    let outputNodes = [];
+    const inputNodes = [];
+    const outputNodes = [];
 
     if (input instanceof Array) {
       inputArr = input;
@@ -167,7 +167,7 @@ export class Graph {
       }
     }
 
-    let edges = [];
+    const edges = [];
     inputNodes.forEach(input => {
       outputNodes.forEach(output => {
         edges.push(this.createEdge().link(input, output));
diff --git a/public/app/core/utils/file_export.ts b/public/app/core/utils/file_export.ts
index f25d340a0be..298a06c64fd 100644
--- a/public/app/core/utils/file_export.ts
+++ b/public/app/core/utils/file_export.ts
@@ -74,7 +74,7 @@ export function convertSeriesListToCsv(seriesList, dateTimeFormat = DEFAULT_DATE
 }
 
 export function exportSeriesListToCsv(seriesList, dateTimeFormat = DEFAULT_DATETIME_FORMAT, excel = false) {
-  let text = convertSeriesListToCsv(seriesList, dateTimeFormat, excel);
+  const text = convertSeriesListToCsv(seriesList, dateTimeFormat, excel);
   saveSaveBlob(text, EXPORT_FILENAME);
 }
 
@@ -115,7 +115,7 @@ export function convertSeriesListToCsvColumns(seriesList, dateTimeFormat = DEFAU
 function mergeSeriesByTime(seriesList) {
   let timestamps = [];
   for (let i = 0; i < seriesList.length; i++) {
-    let seriesPoints = seriesList[i].datapoints;
+    const seriesPoints = seriesList[i].datapoints;
     for (let j = 0; j < seriesPoints.length; j++) {
       timestamps.push(seriesPoints[j][POINT_TIME_INDEX]);
     }
@@ -123,9 +123,9 @@ function mergeSeriesByTime(seriesList) {
   timestamps = sortedUniq(timestamps.sort());
 
   for (let i = 0; i < seriesList.length; i++) {
-    let seriesPoints = seriesList[i].datapoints;
-    let seriesTimestamps = seriesPoints.map(p => p[POINT_TIME_INDEX]);
-    let extendedSeries = [];
+    const seriesPoints = seriesList[i].datapoints;
+    const seriesTimestamps = seriesPoints.map(p => p[POINT_TIME_INDEX]);
+    const extendedSeries = [];
     let pointIndex;
     for (let j = 0; j < timestamps.length; j++) {
       pointIndex = sortedIndexOf(seriesTimestamps, timestamps[j]);
@@ -141,7 +141,7 @@ function mergeSeriesByTime(seriesList) {
 }
 
 export function exportSeriesListToCsvColumns(seriesList, dateTimeFormat = DEFAULT_DATETIME_FORMAT, excel = false) {
-  let text = convertSeriesListToCsvColumns(seriesList, dateTimeFormat, excel);
+  const text = convertSeriesListToCsvColumns(seriesList, dateTimeFormat, excel);
   saveSaveBlob(text, EXPORT_FILENAME);
 }
 
@@ -157,11 +157,11 @@ export function convertTableDataToCsv(table, excel = false) {
 }
 
 export function exportTableDataToCsv(table, excel = false) {
-  let text = convertTableDataToCsv(table, excel);
+  const text = convertTableDataToCsv(table, excel);
   saveSaveBlob(text, EXPORT_FILENAME);
 }
 
 export function saveSaveBlob(payload, fname) {
-  let blob = new Blob([payload], { type: 'text/csv;charset=utf-8;header=present;' });
+  const blob = new Blob([payload], { type: 'text/csv;charset=utf-8;header=present;' });
   saveAs(blob, fname);
 }
diff --git a/public/app/core/utils/outline.ts b/public/app/core/utils/outline.ts
index 94393e781e9..cc06102bfdc 100644
--- a/public/app/core/utils/outline.ts
+++ b/public/app/core/utils/outline.ts
@@ -1,6 +1,6 @@
 // based on http://www.paciellogroup.com/blog/2012/04/how-to-remove-css-outlines-in-an-accessible-manner/
 function outlineFixer() {
-  let d: any = document;
+  const d: any = document;
 
   var style_element = d.createElement('STYLE');
   var dom_events = 'addEventListener' in d;
diff --git a/public/app/core/utils/rangeutil.ts b/public/app/core/utils/rangeutil.ts
index 95cfe42f0b8..8e0f87df686 100644
--- a/public/app/core/utils/rangeutil.ts
+++ b/public/app/core/utils/rangeutil.ts
@@ -92,7 +92,7 @@ function formatDate(date) {
 // now/d
 // if no to <expr> then to now is assumed
 export function describeTextRange(expr: any) {
-  let isLast = expr.indexOf('+') !== 0;
+  const isLast = expr.indexOf('+') !== 0;
   if (expr.indexOf('now') === -1) {
     expr = (isLast ? 'now-' : 'now') + expr;
   }
@@ -108,11 +108,11 @@ export function describeTextRange(expr: any) {
     opt = { from: 'now', to: expr };
   }
 
-  let parts = /^now([-+])(\d+)(\w)/.exec(expr);
+  const parts = /^now([-+])(\d+)(\w)/.exec(expr);
   if (parts) {
-    let unit = parts[3];
-    let amount = parseInt(parts[2]);
-    let span = spans[unit];
+    const unit = parts[3];
+    const amount = parseInt(parts[2]);
+    const span = spans[unit];
     if (span) {
       opt.display = isLast ? 'Last ' : 'Next ';
       opt.display += amount + ' ' + span.display;
diff --git a/public/app/core/utils/sort_by_keys.ts b/public/app/core/utils/sort_by_keys.ts
index 9dff252576a..0020d04f290 100644
--- a/public/app/core/utils/sort_by_keys.ts
+++ b/public/app/core/utils/sort_by_keys.ts
@@ -7,7 +7,7 @@ export default function sortByKeys(input) {
 
   if (_.isPlainObject(input)) {
     var sortedObject = {};
-    for (let key of _.keys(input).sort()) {
+    for (const key of _.keys(input).sort()) {
       sortedObject[key] = sortByKeys(input[key]);
     }
     return sortedObject;
diff --git a/public/app/core/utils/tags.ts b/public/app/core/utils/tags.ts
index 678fd8c94be..d0f244be76b 100644
--- a/public/app/core/utils/tags.ts
+++ b/public/app/core/utils/tags.ts
@@ -67,9 +67,9 @@ const TAG_BORDER_COLORS = [
  * @param name tag name
  */
 export function getTagColorsFromName(name: string): { color: string; borderColor: string } {
-  let hash = djb2(name.toLowerCase());
-  let color = TAG_COLORS[Math.abs(hash % TAG_COLORS.length)];
-  let borderColor = TAG_BORDER_COLORS[Math.abs(hash % TAG_BORDER_COLORS.length)];
+  const hash = djb2(name.toLowerCase());
+  const color = TAG_COLORS[Math.abs(hash % TAG_COLORS.length)];
+  const borderColor = TAG_BORDER_COLORS[Math.abs(hash % TAG_BORDER_COLORS.length)];
   return { color, borderColor };
 }
 
diff --git a/public/app/core/utils/ticks.ts b/public/app/core/utils/ticks.ts
index 66e6a7ce4fc..d87dedccab1 100644
--- a/public/app/core/utils/ticks.ts
+++ b/public/app/core/utils/ticks.ts
@@ -7,7 +7,7 @@
  * @param count Ticks count
  */
 export function tickStep(start: number, stop: number, count: number): number {
-  let e10 = Math.sqrt(50),
+  const e10 = Math.sqrt(50),
     e5 = Math.sqrt(10),
     e2 = Math.sqrt(2);
 
@@ -76,7 +76,7 @@ export function getFlotRange(panelMin, panelMax, datamin, datamax) {
 
   let min = +(panelMin != null ? panelMin : datamin);
   let max = +(panelMax != null ? panelMax : datamax);
-  let delta = max - min;
+  const delta = max - min;
 
   if (delta === 0.0) {
     // Grafana fix: wide Y min and max using increased wideFactor
@@ -123,11 +123,11 @@ export function getFlotTickDecimals(datamin, datamax, axis, height) {
   const { min, max } = getFlotRange(axis.min, axis.max, datamin, datamax);
   const noTicks = 0.3 * Math.sqrt(height);
   const delta = (max - min) / noTicks;
-  let dec = -Math.floor(Math.log(delta) / Math.LN10);
+  const dec = -Math.floor(Math.log(delta) / Math.LN10);
 
-  let magn = Math.pow(10, -dec);
+  const magn = Math.pow(10, -dec);
   // norm is between 1.0 and 10.0
-  let norm = delta / magn;
+  const norm = delta / magn;
   let size;
 
   if (norm < 1.5) {
@@ -159,10 +159,10 @@ export function getFlotTickDecimals(datamin, datamax, axis, height) {
  */
 export function grafanaTimeFormat(ticks, min, max) {
   if (min && max && ticks) {
-    let range = max - min;
-    let secPerTick = range / ticks / 1000;
-    let oneDay = 86400000;
-    let oneYear = 31536000000;
+    const range = max - min;
+    const secPerTick = range / ticks / 1000;
+    const oneDay = 86400000;
+    const oneYear = 31536000000;
 
     if (secPerTick <= 45) {
       return '%H:%M:%S';
@@ -193,7 +193,7 @@ export function logp(value, base) {
  * Get decimal precision of number (3.14 => 2)
  */
 export function getPrecision(num: number): number {
-  let str = num.toString();
+  const str = num.toString();
   return getStringPrecision(str);
 }
 
@@ -201,7 +201,7 @@ export function getPrecision(num: number): number {
  * Get decimal precision of number stored as a string ("3.14" => 2)
  */
 export function getStringPrecision(num: string): number {
-  let dot_index = num.indexOf('.');
+  const dot_index = num.indexOf('.');
   if (dot_index === -1) {
     return 0;
   } else {
diff --git a/public/app/core/utils/url.ts b/public/app/core/utils/url.ts
index b57d5721d57..857e76d9094 100644
--- a/public/app/core/utils/url.ts
+++ b/public/app/core/utils/url.ts
@@ -3,14 +3,14 @@
  */
 
 export function toUrlParams(a) {
-  let s = [];
-  let rbracket = /\[\]$/;
+  const s = [];
+  const rbracket = /\[\]$/;
 
-  let isArray = function(obj) {
+  const isArray = function(obj) {
     return Object.prototype.toString.call(obj) === '[object Array]';
   };
 
-  let add = function(k, v) {
+  const add = function(k, v) {
     v = typeof v === 'function' ? v() : v === null ? '' : v === undefined ? '' : v;
     if (typeof v !== 'boolean') {
       s[s.length] = encodeURIComponent(k) + '=' + encodeURIComponent(v);
@@ -19,7 +19,7 @@ export function toUrlParams(a) {
     }
   };
 
-  let buildParams = function(prefix, obj) {
+  const buildParams = function(prefix, obj) {
     var i, len, key;
 
     if (prefix) {
diff --git a/public/app/core/utils/version.ts b/public/app/core/utils/version.ts
index 6ee1400df51..8b249563d86 100644
--- a/public/app/core/utils/version.ts
+++ b/public/app/core/utils/version.ts
@@ -9,7 +9,7 @@ export class SemVersion {
   meta: string;
 
   constructor(version: string) {
-    let match = versionPattern.exec(version);
+    const match = versionPattern.exec(version);
     if (match) {
       this.major = Number(match[1]);
       this.minor = Number(match[2] || 0);
@@ -19,7 +19,7 @@ export class SemVersion {
   }
 
   isGtOrEq(version: string): boolean {
-    let compared = new SemVersion(version);
+    const compared = new SemVersion(version);
     return !(this.major < compared.major || this.minor < compared.minor || this.patch < compared.patch);
   }
 
@@ -29,6 +29,6 @@ export class SemVersion {
 }
 
 export function isVersionGtOrEq(a: string, b: string): boolean {
-  let a_semver = new SemVersion(a);
+  const a_semver = new SemVersion(a);
   return a_semver.isGtOrEq(b);
 }
diff --git a/public/app/features/alerting/alert_tab_ctrl.ts b/public/app/features/alerting/alert_tab_ctrl.ts
index 79baa1e3f5a..a25d37913d4 100644
--- a/public/app/features/alerting/alert_tab_ctrl.ts
+++ b/public/app/features/alerting/alert_tab_ctrl.ts
@@ -184,7 +184,7 @@ export class AlertTabCtrl {
 
     ThresholdMapper.alertToGraphThresholds(this.panel);
 
-    for (let addedNotification of alert.notifications) {
+    for (const addedNotification of alert.notifications) {
       var model = _.find(this.notifications, { id: addedNotification.id });
       if (model && model.isDefault === false) {
         model.iconClass = this.getNotificationIcon(model.type);
@@ -192,7 +192,7 @@ export class AlertTabCtrl {
       }
     }
 
-    for (let notification of this.notifications) {
+    for (const notification of this.notifications) {
       if (notification.isDefault) {
         notification.iconClass = this.getNotificationIcon(notification.type);
         notification.bgColor = '#00678b';
diff --git a/public/app/features/alerting/notification_edit_ctrl.ts b/public/app/features/alerting/notification_edit_ctrl.ts
index 18b1c4d1d55..eb14766d1fb 100644
--- a/public/app/features/alerting/notification_edit_ctrl.ts
+++ b/public/app/features/alerting/notification_edit_ctrl.ts
@@ -30,7 +30,7 @@ export class AlertNotificationEditCtrl {
         this.notifiers = notifiers;
 
         // add option templates
-        for (let notifier of this.notifiers) {
+        for (const notifier of this.notifiers) {
           this.$templateCache.put(this.getNotifierTemplateId(notifier.type), notifier.optionsTemplate);
         }
 
diff --git a/public/app/features/alerting/threshold_mapper.ts b/public/app/features/alerting/threshold_mapper.ts
index 9142c74b6e3..50324dc18ca 100644
--- a/public/app/features/alerting/threshold_mapper.ts
+++ b/public/app/features/alerting/threshold_mapper.ts
@@ -1,7 +1,7 @@
 export class ThresholdMapper {
   static alertToGraphThresholds(panel) {
     for (var i = 0; i < panel.alert.conditions.length; i++) {
-      let condition = panel.alert.conditions[i];
+      const condition = panel.alert.conditions[i];
       if (condition.type !== 'query') {
         continue;
       }
@@ -11,18 +11,18 @@ export class ThresholdMapper {
 
       switch (evaluator.type) {
         case 'gt': {
-          let value = evaluator.params[0];
+          const value = evaluator.params[0];
           thresholds.push({ value: value, op: 'gt' });
           break;
         }
         case 'lt': {
-          let value = evaluator.params[0];
+          const value = evaluator.params[0];
           thresholds.push({ value: value, op: 'lt' });
           break;
         }
         case 'outside_range': {
-          let value1 = evaluator.params[0];
-          let value2 = evaluator.params[1];
+          const value1 = evaluator.params[0];
+          const value2 = evaluator.params[1];
 
           if (value1 > value2) {
             thresholds.push({ value: value1, op: 'gt' });
@@ -35,8 +35,8 @@ export class ThresholdMapper {
           break;
         }
         case 'within_range': {
-          let value1 = evaluator.params[0];
-          let value2 = evaluator.params[1];
+          const value1 = evaluator.params[0];
+          const value2 = evaluator.params[1];
 
           if (value1 > value2) {
             thresholds.push({ value: value1, op: 'lt' });
diff --git a/public/app/features/annotations/annotations_srv.ts b/public/app/features/annotations/annotations_srv.ts
index 5578a979146..b8def36829a 100644
--- a/public/app/features/annotations/annotations_srv.ts
+++ b/public/app/features/annotations/annotations_srv.ts
@@ -91,7 +91,7 @@ export class AnnotationsSrv {
     var range = this.timeSrv.timeRange();
     var promises = [];
 
-    for (let annotation of dashboard.annotations.list) {
+    for (const annotation of dashboard.annotations.list) {
       if (!annotation.enable) {
         continue;
       }
diff --git a/public/app/features/annotations/event_editor.ts b/public/app/features/annotations/event_editor.ts
index 1f94e978029..90c425438ab 100644
--- a/public/app/features/annotations/event_editor.ts
+++ b/public/app/features/annotations/event_editor.ts
@@ -31,7 +31,7 @@ export class EventEditorCtrl {
       return;
     }
 
-    let saveModel = _.cloneDeep(this.event);
+    const saveModel = _.cloneDeep(this.event);
     saveModel.time = saveModel.time.valueOf();
     saveModel.timeEnd = 0;
 
@@ -85,7 +85,7 @@ export class EventEditorCtrl {
 
 function tryEpochToMoment(timestamp) {
   if (timestamp && _.isNumber(timestamp)) {
-    let epoch = Number(timestamp);
+    const epoch = Number(timestamp);
     return moment(epoch);
   } else {
     return timestamp;
diff --git a/public/app/features/annotations/event_manager.ts b/public/app/features/annotations/event_manager.ts
index 7db6a19f2c6..a6fceac2e54 100644
--- a/public/app/features/annotations/event_manager.ts
+++ b/public/app/features/annotations/event_manager.ts
@@ -125,11 +125,11 @@ export class EventManager {
       }
     }
 
-    let regions = getRegions(annotations);
+    const regions = getRegions(annotations);
     addRegionMarking(regions, flotOptions);
 
-    let eventSectionHeight = 20;
-    let eventSectionMargin = 7;
+    const eventSectionHeight = 20;
+    const eventSectionMargin = 7;
     flotOptions.grid.eventSectionHeight = eventSectionMargin;
     flotOptions.xaxis.eventSectionHeight = eventSectionHeight;
 
@@ -147,8 +147,8 @@ function getRegions(events) {
 }
 
 function addRegionMarking(regions, flotOptions) {
-  let markings = flotOptions.grid.markings;
-  let defaultColor = DEFAULT_ANNOTATION_COLOR;
+  const markings = flotOptions.grid.markings;
+  const defaultColor = DEFAULT_ANNOTATION_COLOR;
   let fillColor;
 
   _.each(regions, region => {
@@ -167,7 +167,7 @@ function addRegionMarking(regions, flotOptions) {
 }
 
 function addAlphaToRGB(colorString: string, alpha: number): string {
-  let color = tinycolor(colorString);
+  const color = tinycolor(colorString);
   if (color.isValid()) {
     color.setAlpha(alpha);
     return color.toRgbString();
diff --git a/public/app/features/annotations/events_processing.ts b/public/app/features/annotations/events_processing.ts
index 667285d7d43..6e610fb1457 100644
--- a/public/app/features/annotations/events_processing.ts
+++ b/public/app/features/annotations/events_processing.ts
@@ -7,20 +7,20 @@ import _ from 'lodash';
  * @param options
  */
 export function makeRegions(annotations, options) {
-  let [regionEvents, singleEvents] = _.partition(annotations, 'regionId');
-  let regions = getRegions(regionEvents, options.range);
+  const [regionEvents, singleEvents] = _.partition(annotations, 'regionId');
+  const regions = getRegions(regionEvents, options.range);
   annotations = _.concat(regions, singleEvents);
   return annotations;
 }
 
 function getRegions(events, range) {
-  let region_events = _.filter(events, event => {
+  const region_events = _.filter(events, event => {
     return event.regionId;
   });
   let regions = _.groupBy(region_events, 'regionId');
   regions = _.compact(
     _.map(regions, region_events => {
-      let region_obj = _.head(region_events);
+      const region_obj = _.head(region_events);
       if (region_events && region_events.length > 1) {
         region_obj.timeEnd = region_events[1].time;
         region_obj.isRegion = true;
@@ -57,9 +57,9 @@ export function dedupAnnotations(annotations) {
   let dedup = [];
 
   // Split events by annotationId property existence
-  let events = _.partition(annotations, 'id');
+  const events = _.partition(annotations, 'id');
 
-  let eventsById = _.groupBy(events[0], 'id');
+  const eventsById = _.groupBy(events[0], 'id');
   dedup = _.map(eventsById, eventGroup => {
     if (eventGroup.length > 1 && !_.every(eventGroup, isPanelAlert)) {
       // Get first non-panel alert
diff --git a/public/app/features/annotations/specs/annotations_srv.test.ts b/public/app/features/annotations/specs/annotations_srv.test.ts
index 7db7b6c9f05..97696767536 100644
--- a/public/app/features/annotations/specs/annotations_srv.test.ts
+++ b/public/app/features/annotations/specs/annotations_srv.test.ts
@@ -3,7 +3,7 @@ import 'app/features/dashboard/time_srv';
 import { AnnotationsSrv } from '../annotations_srv';
 
 describe('AnnotationsSrv', function() {
-  let $rootScope = {
+  const $rootScope = {
     onAppEvent: jest.fn(),
   };
   let $q;
@@ -11,7 +11,7 @@ describe('AnnotationsSrv', function() {
   let backendSrv;
   let timeSrv;
 
-  let annotationsSrv = new AnnotationsSrv($rootScope, $q, datasourceSrv, backendSrv, timeSrv);
+  const annotationsSrv = new AnnotationsSrv($rootScope, $q, datasourceSrv, backendSrv, timeSrv);
 
   describe('When translating the query result', () => {
     const annotationSource = {
diff --git a/public/app/features/annotations/specs/annotations_srv_specs.test.ts b/public/app/features/annotations/specs/annotations_srv_specs.test.ts
index 35def83e4a9..49457f34d05 100644
--- a/public/app/features/annotations/specs/annotations_srv_specs.test.ts
+++ b/public/app/features/annotations/specs/annotations_srv_specs.test.ts
@@ -24,7 +24,7 @@ describe('Annotations', () => {
         { id: 2, time: 2 },
       ];
 
-      let regions = makeRegions(testAnnotations, { range: range });
+      const regions = makeRegions(testAnnotations, { range: range });
       expect(regions).toEqual(expectedAnnotations);
     });
 
@@ -33,7 +33,7 @@ describe('Annotations', () => {
       testAnnotations = [{ id: 5, time: 4, regionId: 5 }];
       const expectedAnnotations = [{ id: 5, regionId: 5, isRegion: true, time: 4, timeEnd: 7 }];
 
-      let regions = makeRegions(testAnnotations, { range: range });
+      const regions = makeRegions(testAnnotations, { range: range });
       expect(regions).toEqual(expectedAnnotations);
     });
   });
@@ -49,7 +49,7 @@ describe('Annotations', () => {
       ];
       const expectedAnnotations = [{ id: 1, time: 1 }, { id: 2, time: 2 }, { id: 5, time: 5 }];
 
-      let deduplicated = dedupAnnotations(testAnnotations);
+      const deduplicated = dedupAnnotations(testAnnotations);
       expect(deduplicated).toEqual(expectedAnnotations);
     });
 
@@ -63,7 +63,7 @@ describe('Annotations', () => {
       ];
       const expectedAnnotations = [{ id: 1, time: 1 }, { id: 2, time: 2 }, { id: 5, time: 5 }];
 
-      let deduplicated = dedupAnnotations(testAnnotations);
+      const deduplicated = dedupAnnotations(testAnnotations);
       expect(deduplicated).toEqual(expectedAnnotations);
     });
   });
diff --git a/public/app/features/dashboard/ad_hoc_filters.ts b/public/app/features/dashboard/ad_hoc_filters.ts
index ee57db23675..412761dc716 100644
--- a/public/app/features/dashboard/ad_hoc_filters.ts
+++ b/public/app/features/dashboard/ad_hoc_filters.ts
@@ -30,7 +30,7 @@ export class AdHocFiltersCtrl {
     if (this.variable.value && !_.isArray(this.variable.value)) {
     }
 
-    for (let tag of this.variable.filters) {
+    for (const tag of this.variable.filters) {
       if (this.segments.length > 0) {
         this.segments.push(this.uiSegmentSrv.newCondition('AND'));
       }
diff --git a/public/app/features/dashboard/change_tracker.ts b/public/app/features/dashboard/change_tracker.ts
index 745b76ce347..1417510bb2c 100644
--- a/public/app/features/dashboard/change_tracker.ts
+++ b/public/app/features/dashboard/change_tracker.ts
@@ -94,13 +94,13 @@ export class ChangeTracker {
   // remove stuff that should not count in diff
   cleanDashboardFromIgnoredChanges(dashData) {
     // need to new up the domain model class to get access to expand / collapse row logic
-    let model = new DashboardModel(dashData);
+    const model = new DashboardModel(dashData);
 
     // Expand all rows before making comparison. This is required because row expand / collapse
     // change order of panel array and panel positions.
     model.expandRows();
 
-    let dash = model.getSaveModelClone();
+    const dash = model.getSaveModelClone();
 
     // ignore time and refresh
     dash.time = 0;
@@ -138,8 +138,8 @@ export class ChangeTracker {
   }
 
   hasChanges() {
-    let current = this.cleanDashboardFromIgnoredChanges(this.current.getSaveModelClone());
-    let original = this.cleanDashboardFromIgnoredChanges(this.original);
+    const current = this.cleanDashboardFromIgnoredChanges(this.current.getSaveModelClone());
+    const original = this.cleanDashboardFromIgnoredChanges(this.original);
 
     var currentTimepicker = _.find(current.nav, { type: 'timepicker' });
     var originalTimepicker = _.find(original.nav, { type: 'timepicker' });
diff --git a/public/app/features/dashboard/dashboard_import_ctrl.ts b/public/app/features/dashboard/dashboard_import_ctrl.ts
index 73e9e316b4e..b70a1847602 100644
--- a/public/app/features/dashboard/dashboard_import_ctrl.ts
+++ b/public/app/features/dashboard/dashboard_import_ctrl.ts
@@ -51,7 +51,7 @@ export class DashboardImportCtrl {
     this.inputs = [];
 
     if (this.dash.__inputs) {
-      for (let input of this.dash.__inputs) {
+      for (const input of this.dash.__inputs) {
         var inputModel = {
           name: input.name,
           label: input.label,
@@ -95,7 +95,7 @@ export class DashboardImportCtrl {
 
   inputValueChanged() {
     this.inputsValid = true;
-    for (let input of this.inputs) {
+    for (const input of this.inputs) {
       if (!input.value) {
         this.inputsValid = false;
       }
diff --git a/public/app/features/dashboard/dashboard_migration.ts b/public/app/features/dashboard/dashboard_migration.ts
index 1d319929bfd..3753cbe7c55 100644
--- a/public/app/features/dashboard/dashboard_migration.ts
+++ b/public/app/features/dashboard/dashboard_migration.ts
@@ -389,7 +389,7 @@ export class DashboardMigrator {
 
   upgradeToGridLayout(old) {
     let yPos = 0;
-    let widthFactor = GRID_COLUMN_COUNT / 12;
+    const widthFactor = GRID_COLUMN_COUNT / 12;
 
     const maxPanelId = _.max(
       _.flattenDeep(
@@ -407,15 +407,15 @@ export class DashboardMigrator {
     // Add special "row" panels if even one row is collapsed, repeated or has visible title
     const showRows = _.some(old.rows, row => row.collapse || row.showTitle || row.repeat);
 
-    for (let row of old.rows) {
+    for (const row of old.rows) {
       if (row.repeatIteration) {
         continue;
       }
 
-      let height: any = row.height || DEFAULT_ROW_HEIGHT;
+      const height: any = row.height || DEFAULT_ROW_HEIGHT;
       const rowGridHeight = getGridHeight(height);
 
-      let rowPanel: any = {};
+      const rowPanel: any = {};
       let rowPanelModel: PanelModel;
       if (showRows) {
         // add special row panel
@@ -436,9 +436,9 @@ export class DashboardMigrator {
         yPos++;
       }
 
-      let rowArea = new RowArea(rowGridHeight, GRID_COLUMN_COUNT, yPos);
+      const rowArea = new RowArea(rowGridHeight, GRID_COLUMN_COUNT, yPos);
 
-      for (let panel of row.panels) {
+      for (const panel of row.panels) {
         panel.span = panel.span || DEFAULT_PANEL_SPAN;
         if (panel.minSpan) {
           panel.minSpan = Math.min(GRID_COLUMN_COUNT, GRID_COLUMN_COUNT / 12 * panel.minSpan);
@@ -446,7 +446,7 @@ export class DashboardMigrator {
         const panelWidth = Math.floor(panel.span) * widthFactor;
         const panelHeight = panel.height ? getGridHeight(panel.height) : rowGridHeight;
 
-        let panelPos = rowArea.getPanelPosition(panelHeight, panelWidth);
+        const panelPos = rowArea.getPanelPosition(panelHeight, panelWidth);
         yPos = rowArea.yPos;
         panel.gridPos = {
           x: panelPos.x,
diff --git a/public/app/features/dashboard/dashboard_model.ts b/public/app/features/dashboard/dashboard_model.ts
index 92392fc80e8..8f61cf06c60 100644
--- a/public/app/features/dashboard/dashboard_model.ts
+++ b/public/app/features/dashboard/dashboard_model.ts
@@ -95,7 +95,7 @@ export class DashboardModel {
 
   addBuiltInAnnotationQuery() {
     let found = false;
-    for (let item of this.annotations.list) {
+    for (const item of this.annotations.list) {
       if (item.builtIn === 1) {
         found = true;
         break;
@@ -138,7 +138,7 @@ export class DashboardModel {
 
   // cleans meta data and other non persistent state
   getSaveModelClone(options?) {
-    let defaults = _.defaults(options || {}, {
+    const defaults = _.defaults(options || {}, {
       saveVariables: true,
       saveTimerange: true,
     });
@@ -160,8 +160,8 @@ export class DashboardModel {
 
     if (!defaults.saveVariables) {
       for (let i = 0; i < copy.templating.list.length; i++) {
-        let current = copy.templating.list[i];
-        let original = _.find(this.originalTemplating, { name: current.name, type: current.type });
+        const current = copy.templating.list[i];
+        const original = _.find(this.originalTemplating, { name: current.name, type: current.type });
 
         if (!original) {
           continue;
@@ -213,13 +213,13 @@ export class DashboardModel {
   getNextPanelId() {
     let max = 0;
 
-    for (let panel of this.panels) {
+    for (const panel of this.panels) {
       if (panel.id > max) {
         max = panel.id;
       }
 
       if (panel.collapsed) {
-        for (let rowPanel of panel.panels) {
+        for (const rowPanel of panel.panels) {
           if (rowPanel.id > max) {
             max = rowPanel.id;
           }
@@ -237,7 +237,7 @@ export class DashboardModel {
   }
 
   getPanelById(id) {
-    for (let panel of this.panels) {
+    for (const panel of this.panels) {
       if (panel.id === id) {
         return panel;
       }
@@ -248,7 +248,7 @@ export class DashboardModel {
   addPanel(panelData) {
     panelData.id = this.getNextPanelId();
 
-    let panel = new PanelModel(panelData);
+    const panel = new PanelModel(panelData);
 
     this.panels.unshift(panel);
 
@@ -273,15 +273,15 @@ export class DashboardModel {
     }
 
     this.iteration = (this.iteration || new Date().getTime()) + 1;
-    let panelsToRemove = [];
+    const panelsToRemove = [];
 
     // cleanup scopedVars
-    for (let panel of this.panels) {
+    for (const panel of this.panels) {
       delete panel.scopedVars;
     }
 
     for (let i = 0; i < this.panels.length; i++) {
-      let panel = this.panels[i];
+      const panel = this.panels[i];
       if ((!panel.repeat || panel.repeatedByRow) && panel.repeatPanelId && panel.repeatIteration !== this.iteration) {
         panelsToRemove.push(panel);
       }
@@ -304,7 +304,7 @@ export class DashboardModel {
     this.iteration = (this.iteration || new Date().getTime()) + 1;
 
     for (let i = 0; i < this.panels.length; i++) {
-      let panel = this.panels[i];
+      const panel = this.panels[i];
       if (panel.repeat) {
         this.repeatPanel(panel, i);
       }
@@ -315,9 +315,9 @@ export class DashboardModel {
   }
 
   cleanUpRowRepeats(rowPanels) {
-    let panelsToRemove = [];
+    const panelsToRemove = [];
     for (let i = 0; i < rowPanels.length; i++) {
-      let panel = rowPanels[i];
+      const panel = rowPanels[i];
       if (!panel.repeat && panel.repeatPanelId) {
         panelsToRemove.push(panel);
       }
@@ -333,16 +333,16 @@ export class DashboardModel {
 
     let rowPanels = row.panels;
     if (!row.collapsed) {
-      let rowPanelIndex = _.findIndex(this.panels, p => p.id === row.id);
+      const rowPanelIndex = _.findIndex(this.panels, p => p.id === row.id);
       rowPanels = this.getRowPanels(rowPanelIndex);
     }
 
     this.cleanUpRowRepeats(rowPanels);
 
     for (let i = 0; i < rowPanels.length; i++) {
-      let panel = rowPanels[i];
+      const panel = rowPanels[i];
       if (panel.repeat) {
-        let panelIndex = _.findIndex(this.panels, p => p.id === panel.id);
+        const panelIndex = _.findIndex(this.panels, p => p.id === panel.id);
         this.repeatPanel(panel, panelIndex);
       }
     }
@@ -354,7 +354,7 @@ export class DashboardModel {
       return sourcePanel;
     }
 
-    let clone = new PanelModel(sourcePanel.getSaveModel());
+    const clone = new PanelModel(sourcePanel.getSaveModel());
     clone.id = this.getNextPanelId();
 
     // insert after source panel + value index
@@ -370,13 +370,13 @@ export class DashboardModel {
     // if first clone return source
     if (valueIndex === 0) {
       if (!sourceRowPanel.collapsed) {
-        let rowPanels = this.getRowPanels(sourcePanelIndex);
+        const rowPanels = this.getRowPanels(sourcePanelIndex);
         sourceRowPanel.panels = rowPanels;
       }
       return sourceRowPanel;
     }
 
-    let clone = new PanelModel(sourceRowPanel.getSaveModel());
+    const clone = new PanelModel(sourceRowPanel.getSaveModel());
     // for row clones we need to figure out panels under row to clone and where to insert clone
     let rowPanels, insertPos;
     if (sourceRowPanel.collapsed) {
@@ -397,7 +397,7 @@ export class DashboardModel {
   }
 
   repeatPanel(panel: PanelModel, panelIndex: number) {
-    let variable = _.find(this.templating.list, { name: panel.repeat });
+    const variable = _.find(this.templating.list, { name: panel.repeat });
     if (!variable) {
       return;
     }
@@ -407,13 +407,13 @@ export class DashboardModel {
       return;
     }
 
-    let selectedOptions = this.getSelectedVariableOptions(variable);
-    let minWidth = panel.minSpan || 6;
+    const selectedOptions = this.getSelectedVariableOptions(variable);
+    const minWidth = panel.minSpan || 6;
     let xPos = 0;
     let yPos = panel.gridPos.y;
 
     for (let index = 0; index < selectedOptions.length; index++) {
-      let option = selectedOptions[index];
+      const option = selectedOptions[index];
       let copy;
 
       copy = this.getPanelRepeatClone(panel, index, panelIndex);
@@ -443,9 +443,9 @@ export class DashboardModel {
     }
 
     // Update gridPos for panels below
-    let yOffset = yPos - panel.gridPos.y;
+    const yOffset = yPos - panel.gridPos.y;
     if (yOffset > 0) {
-      let panelBelowIndex = panelIndex + selectedOptions.length;
+      const panelBelowIndex = panelIndex + selectedOptions.length;
       for (let i = panelBelowIndex; i < this.panels.length; i++) {
         this.panels[i].gridPos.y += yOffset;
       }
@@ -453,7 +453,7 @@ export class DashboardModel {
   }
 
   repeatRow(panel: PanelModel, panelIndex: number, variable) {
-    let selectedOptions = this.getSelectedVariableOptions(variable);
+    const selectedOptions = this.getSelectedVariableOptions(variable);
     let yPos = panel.gridPos.y;
 
     function setScopedVars(panel, variableOption) {
@@ -462,12 +462,12 @@ export class DashboardModel {
     }
 
     for (let optionIndex = 0; optionIndex < selectedOptions.length; optionIndex++) {
-      let option = selectedOptions[optionIndex];
-      let rowCopy = this.getRowRepeatClone(panel, optionIndex, panelIndex);
+      const option = selectedOptions[optionIndex];
+      const rowCopy = this.getRowRepeatClone(panel, optionIndex, panelIndex);
       setScopedVars(rowCopy, option);
 
-      let rowHeight = this.getRowHeight(rowCopy);
-      let rowPanels = rowCopy.panels || [];
+      const rowHeight = this.getRowHeight(rowCopy);
+      const rowPanels = rowCopy.panels || [];
       let panelBelowIndex;
 
       if (panel.collapsed) {
@@ -483,11 +483,11 @@ export class DashboardModel {
         panelBelowIndex = panelIndex + optionIndex + 1;
       } else {
         // insert after 'row' panel
-        let insertPos = panelIndex + (rowPanels.length + 1) * optionIndex + 1;
+        const insertPos = panelIndex + (rowPanels.length + 1) * optionIndex + 1;
         _.each(rowPanels, (rowPanel, i) => {
           setScopedVars(rowPanel, option);
           if (optionIndex > 0) {
-            let cloneRowPanel = new PanelModel(rowPanel);
+            const cloneRowPanel = new PanelModel(rowPanel);
             this.updateRepeatedPanelIds(cloneRowPanel, true);
             // For exposed row additionally set proper Y grid position and add it to dashboard panels
             cloneRowPanel.gridPos.y += rowHeight * optionIndex;
@@ -650,29 +650,29 @@ export class DashboardModel {
   formatDate(date, format?) {
     date = moment.isMoment(date) ? date : moment(date);
     format = format || 'YYYY-MM-DD HH:mm:ss';
-    let timezone = this.getTimezone();
+    const timezone = this.getTimezone();
 
     return timezone === 'browser' ? moment(date).format(format) : moment.utc(date).format(format);
   }
 
   destroy() {
     this.events.removeAllListeners();
-    for (let panel of this.panels) {
+    for (const panel of this.panels) {
       panel.destroy();
     }
   }
 
   toggleRow(row: PanelModel) {
-    let rowIndex = _.indexOf(this.panels, row);
+    const rowIndex = _.indexOf(this.panels, row);
 
     if (row.collapsed) {
       row.collapsed = false;
-      let hasRepeat = _.some(row.panels, p => p.repeat);
+      const hasRepeat = _.some(row.panels, p => p.repeat);
 
       if (row.panels.length > 0) {
         // Use first panel to figure out if it was moved or pushed
-        let firstPanel = row.panels[0];
-        let yDiff = firstPanel.gridPos.y - (row.gridPos.y + row.gridPos.h);
+        const firstPanel = row.panels[0];
+        const yDiff = firstPanel.gridPos.y - (row.gridPos.y + row.gridPos.h);
 
         // start inserting after row
         let insertPos = rowIndex + 1;
@@ -680,7 +680,7 @@ export class DashboardModel {
         // needed to know home much panels below should be pushed down
         let yMax = row.gridPos.y;
 
-        for (let panel of row.panels) {
+        for (const panel of row.panels) {
           // make sure y is adjusted (in case row moved while collapsed)
           // console.log('yDiff', yDiff);
           panel.gridPos.y -= yDiff;
@@ -713,7 +713,7 @@ export class DashboardModel {
       return;
     }
 
-    let rowPanels = this.getRowPanels(rowIndex);
+    const rowPanels = this.getRowPanels(rowIndex);
 
     // remove panels
     _.pull(this.panels, ...rowPanels);
@@ -729,10 +729,10 @@ export class DashboardModel {
    * Will return all panels after rowIndex until it encounters another row
    */
   getRowPanels(rowIndex: number): PanelModel[] {
-    let rowPanels = [];
+    const rowPanels = [];
 
     for (let index = rowIndex + 1; index < this.panels.length; index++) {
-      let panel = this.panels[index];
+      const panel = this.panels[index];
 
       // break when encountering another row
       if (panel.type === 'row') {
@@ -791,7 +791,7 @@ export class DashboardModel {
   }
 
   private updateSchema(old) {
-    let migrator = new DashboardMigrator(this);
+    const migrator = new DashboardMigrator(this);
     migrator.updateSchema(old);
   }
 
diff --git a/public/app/features/dashboard/dashgrid/AddPanelPanel.tsx b/public/app/features/dashboard/dashgrid/AddPanelPanel.tsx
index f1f2290ce40..9459fc41753 100644
--- a/public/app/features/dashboard/dashgrid/AddPanelPanel.tsx
+++ b/public/app/features/dashboard/dashgrid/AddPanelPanel.tsx
@@ -68,18 +68,18 @@ export class AddPanelPanel extends React.Component<AddPanelPanelProps, AddPanelP
   }
 
   getCopiedPanelPlugins(filter) {
-    let panels = _.chain(config.panels)
+    const panels = _.chain(config.panels)
       .filter({ hideFromList: false })
       .map(item => item)
       .value();
     let copiedPanels = [];
 
-    let copiedPanelJson = store.get(LS_PANEL_COPY_KEY);
+    const copiedPanelJson = store.get(LS_PANEL_COPY_KEY);
     if (copiedPanelJson) {
-      let copiedPanel = JSON.parse(copiedPanelJson);
-      let pluginInfo = _.find(panels, { id: copiedPanel.type });
+      const copiedPanel = JSON.parse(copiedPanelJson);
+      const pluginInfo = _.find(panels, { id: copiedPanel.type });
       if (pluginInfo) {
-        let pluginCopy = _.cloneDeep(pluginInfo);
+        const pluginCopy = _.cloneDeep(pluginInfo);
         pluginCopy.name = copiedPanel.title;
         pluginCopy.sort = -1;
         pluginCopy.defaults = copiedPanel;
@@ -129,7 +129,7 @@ export class AddPanelPanel extends React.Component<AddPanelPanelProps, AddPanelP
   }
 
   renderText(text: string) {
-    let searchWords = this.state.filter.split('');
+    const searchWords = this.state.filter.split('');
     return <Highlighter highlightClassName="highlight-search-match" textToHighlight={text} searchWords={searchWords} />;
   }
 
@@ -156,7 +156,7 @@ export class AddPanelPanel extends React.Component<AddPanelPanelProps, AddPanelP
 
   filterKeyPress(evt) {
     if (evt.key === 'Enter') {
-      let panel = _.head(this.state.panelPlugins);
+      const panel = _.head(this.state.panelPlugins);
       if (panel) {
         this.onAddPanel(panel);
       }
@@ -164,7 +164,7 @@ export class AddPanelPanel extends React.Component<AddPanelPanelProps, AddPanelP
   }
 
   filterPanels(panels, filter) {
-    let regex = new RegExp(filter, 'i');
+    const regex = new RegExp(filter, 'i');
     return panels.filter(panel => {
       return regex.test(panel.name);
     });
@@ -189,12 +189,12 @@ export class AddPanelPanel extends React.Component<AddPanelPanelProps, AddPanelP
   }
 
   render() {
-    let addClass = classNames({
+    const addClass = classNames({
       'active active--panel': this.state.tab === 'Add',
       '': this.state.tab === 'Copy',
     });
 
-    let copyClass = classNames({
+    const copyClass = classNames({
       '': this.state.tab === 'Add',
       'active active--panel': this.state.tab === 'Copy',
     });
diff --git a/public/app/features/dashboard/dashgrid/DashboardGrid.tsx b/public/app/features/dashboard/dashgrid/DashboardGrid.tsx
index 290e587eace..132e9b65a55 100644
--- a/public/app/features/dashboard/dashgrid/DashboardGrid.tsx
+++ b/public/app/features/dashboard/dashgrid/DashboardGrid.tsx
@@ -94,8 +94,8 @@ export class DashboardGrid extends React.Component<DashboardGridProps, any> {
     const layout = [];
     this.panelMap = {};
 
-    for (let panel of this.dashboard.panels) {
-      let stringId = panel.id.toString();
+    for (const panel of this.dashboard.panels) {
+      const stringId = panel.id.toString();
       this.panelMap[stringId] = panel;
 
       if (!panel.gridPos) {
@@ -103,7 +103,7 @@ export class DashboardGrid extends React.Component<DashboardGridProps, any> {
         continue;
       }
 
-      let panelPos: any = {
+      const panelPos: any = {
         i: stringId,
         x: panel.gridPos.x,
         y: panel.gridPos.y,
@@ -174,7 +174,7 @@ export class DashboardGrid extends React.Component<DashboardGridProps, any> {
   renderPanels() {
     const panelElements = [];
 
-    for (let panel of this.dashboard.panels) {
+    for (const panel of this.dashboard.panels) {
       const panelClasses = classNames({ panel: true, 'panel--fullscreen': panel.fullscreen });
       panelElements.push(
         <div key={panel.id.toString()} className={panelClasses}>
diff --git a/public/app/features/dashboard/dashnav/dashnav.ts b/public/app/features/dashboard/dashnav/dashnav.ts
index 628f09349d3..a83efe7d390 100644
--- a/public/app/features/dashboard/dashnav/dashnav.ts
+++ b/public/app/features/dashboard/dashnav/dashnav.ts
@@ -22,7 +22,7 @@ export class DashNavCtrl {
   }
 
   toggleSettings() {
-    let search = this.$location.search();
+    const search = this.$location.search();
     if (search.editview) {
       delete search.editview;
     } else {
@@ -32,7 +32,7 @@ export class DashNavCtrl {
   }
 
   close() {
-    let search = this.$location.search();
+    const search = this.$location.search();
     if (search.editview) {
       delete search.editview;
     } else if (search.fullscreen) {
diff --git a/public/app/features/dashboard/export/export_modal.ts b/public/app/features/dashboard/export/export_modal.ts
index 2e61ce9f8a8..d314f13be4b 100644
--- a/public/app/features/dashboard/export/export_modal.ts
+++ b/public/app/features/dashboard/export/export_modal.ts
@@ -29,7 +29,7 @@ export class DashExportCtrl {
 
   saveJson() {
     var clone = this.dash;
-    let editScope = this.$rootScope.$new();
+    const editScope = this.$rootScope.$new();
     editScope.object = clone;
     editScope.enableCopy = true;
 
diff --git a/public/app/features/dashboard/export/exporter.ts b/public/app/features/dashboard/export/exporter.ts
index fc24de76fcc..91e9f12ae54 100644
--- a/public/app/features/dashboard/export/exporter.ts
+++ b/public/app/features/dashboard/export/exporter.ts
@@ -24,7 +24,7 @@ export class DashboardExporter {
     var promises = [];
     var variableLookup: any = {};
 
-    for (let variable of saveModel.templating.list) {
+    for (const variable of saveModel.templating.list) {
       variableLookup[variable.name] = variable;
     }
 
@@ -69,7 +69,7 @@ export class DashboardExporter {
       }
 
       if (panel.targets) {
-        for (let target of panel.targets) {
+        for (const target of panel.targets) {
           if (target.datasource !== undefined) {
             templateizeDatasourceUsage(target);
           }
@@ -88,19 +88,19 @@ export class DashboardExporter {
     };
 
     // check up panel data sources
-    for (let panel of saveModel.panels) {
+    for (const panel of saveModel.panels) {
       processPanel(panel);
 
       // handle collapsed rows
       if (panel.collapsed !== undefined && panel.collapsed === true && panel.panels) {
-        for (let rowPanel of panel.panels) {
+        for (const rowPanel of panel.panels) {
           processPanel(rowPanel);
         }
       }
     }
 
     // templatize template vars
-    for (let variable of saveModel.templating.list) {
+    for (const variable of saveModel.templating.list) {
       if (variable.type === 'query') {
         templateizeDatasourceUsage(variable);
         variable.options = [];
@@ -110,7 +110,7 @@ export class DashboardExporter {
     }
 
     // templatize annotations vars
-    for (let annotationDef of saveModel.annotations.list) {
+    for (const annotationDef of saveModel.annotations.list) {
       templateizeDatasourceUsage(annotationDef);
     }
 
@@ -129,7 +129,7 @@ export class DashboardExporter {
         });
 
         // templatize constants
-        for (let variable of saveModel.templating.list) {
+        for (const variable of saveModel.templating.list) {
           if (variable.type === 'constant') {
             var refName = 'VAR_' + variable.name.replace(' ', '_').toUpperCase();
             inputs.push({
diff --git a/public/app/features/dashboard/history/history.ts b/public/app/features/dashboard/history/history.ts
index be6ad5af1ba..3563ccc7766 100644
--- a/public/app/features/dashboard/history/history.ts
+++ b/public/app/features/dashboard/history/history.ts
@@ -67,7 +67,7 @@ export class HistoryListCtrl {
   }
 
   revisionSelectionChanged() {
-    let selected = _.filter(this.revisions, { checked: true }).length;
+    const selected = _.filter(this.revisions, { checked: true }).length;
     this.canCompare = selected === 2;
   }
 
@@ -134,7 +134,7 @@ export class HistoryListCtrl {
       .getHistoryList(this.dashboard, options)
       .then(revisions => {
         // set formatted dates & default values
-        for (let rev of revisions) {
+        for (const rev of revisions) {
           rev.createdDateString = this.formatDate(rev.created);
           rev.ageString = this.formatBasicDate(rev.created);
           rev.checked = false;
diff --git a/public/app/features/dashboard/settings/settings.ts b/public/app/features/dashboard/settings/settings.ts
index 457cac5af72..1d4a70d42aa 100755
--- a/public/app/features/dashboard/settings/settings.ts
+++ b/public/app/features/dashboard/settings/settings.ts
@@ -109,7 +109,7 @@ export class SettingsCtrl {
     const params = this.$location.search();
     const url = this.$location.path();
 
-    for (let section of this.sections) {
+    for (const section of this.sections) {
       const sectionParams = _.defaults({ editview: section.id }, params);
       section.url = config.appSubUrl + url + '?' + $.param(sectionParams);
     }
diff --git a/public/app/features/dashboard/shareModalCtrl.ts b/public/app/features/dashboard/shareModalCtrl.ts
index c32c2a79190..fff307c2510 100644
--- a/public/app/features/dashboard/shareModalCtrl.ts
+++ b/public/app/features/dashboard/shareModalCtrl.ts
@@ -91,7 +91,7 @@ export function ShareModalCtrl($scope, $rootScope, $location, $timeout, timeSrv,
   // This function will try to return the proper full name of the local timezone
   // Chrome does not handle the timezone offset (but phantomjs does)
   $scope.getLocalTimeZone = function() {
-    let utcOffset = '&tz=UTC' + encodeURIComponent(moment().format('Z'));
+    const utcOffset = '&tz=UTC' + encodeURIComponent(moment().format('Z'));
 
     // Older browser does not the internationalization API
     if (!(<any>window).Intl) {
diff --git a/public/app/features/dashboard/specs/dashboard_migration.test.ts b/public/app/features/dashboard/specs/dashboard_migration.test.ts
index 07a29d58e65..f440dbb49f2 100644
--- a/public/app/features/dashboard/specs/dashboard_migration.test.ts
+++ b/public/app/features/dashboard/specs/dashboard_migration.test.ts
@@ -151,18 +151,18 @@ describe('DashboardModel', function() {
 
     it('should create proper grid', function() {
       model.rows = [createRow({ collapse: false, height: 8 }, [[6], [6]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [{ x: 0, y: 0, w: 12, h: 8 }, { x: 12, y: 0, w: 12, h: 8 }];
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [{ x: 0, y: 0, w: 12, h: 8 }, { x: 12, y: 0, w: 12, h: 8 }];
 
       expect(panelGridPos).toEqual(expectedGrid);
     });
 
     it('should add special "row" panel if row is collapsed', function() {
       model.rows = [createRow({ collapse: true, height: 8 }, [[6], [6]]), createRow({ height: 8 }, [[12]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 24, h: 8 }, // row
         { x: 0, y: 1, w: 24, h: 8 }, // row
         { x: 0, y: 2, w: 24, h: 8 },
@@ -176,9 +176,9 @@ describe('DashboardModel', function() {
         createRow({ showTitle: true, title: 'Row', height: 8 }, [[6], [6]]),
         createRow({ height: 8 }, [[12]]),
       ];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 24, h: 8 }, // row
         { x: 0, y: 1, w: 12, h: 8 },
         { x: 12, y: 1, w: 12, h: 8 },
@@ -196,9 +196,9 @@ describe('DashboardModel', function() {
         createRow({ height: 8 }, [[12], [6], [6]]),
         createRow({ collapse: true, height: 8 }, [[12]]),
       ];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 24, h: 8 }, // row
         { x: 0, y: 1, w: 24, h: 8 }, // row
         { x: 0, y: 2, w: 24, h: 8 },
@@ -214,9 +214,9 @@ describe('DashboardModel', function() {
 
     it('should add all rows if even one collapsed or titled row is present', function() {
       model.rows = [createRow({ collapse: true, height: 8 }, [[6], [6]]), createRow({ height: 8 }, [[12]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 24, h: 8 }, // row
         { x: 0, y: 1, w: 24, h: 8 }, // row
         { x: 0, y: 2, w: 24, h: 8 },
@@ -230,9 +230,9 @@ describe('DashboardModel', function() {
         createRow({ height: 6 }, [[6], [6, 3], [6, 3]]),
         createRow({ height: 6 }, [[4], [4], [4, 3], [4, 3]]),
       ];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 12, h: 6 },
         { x: 12, y: 0, w: 12, h: 3 },
         { x: 12, y: 3, w: 12, h: 3 },
@@ -247,9 +247,9 @@ describe('DashboardModel', function() {
 
     it('should place panel to the right side of panel having bigger height', function() {
       model.rows = [createRow({ height: 6 }, [[4], [2, 3], [4, 6], [2, 3], [2, 3]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 8, h: 6 },
         { x: 8, y: 0, w: 4, h: 3 },
         { x: 12, y: 0, w: 8, h: 6 },
@@ -262,9 +262,9 @@ describe('DashboardModel', function() {
 
     it('should fill current row if it possible', function() {
       model.rows = [createRow({ height: 9 }, [[4], [2, 3], [4, 6], [2, 3], [2, 3], [8, 3]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 8, h: 9 },
         { x: 8, y: 0, w: 4, h: 3 },
         { x: 12, y: 0, w: 8, h: 6 },
@@ -278,9 +278,9 @@ describe('DashboardModel', function() {
 
     it('should fill current row if it possible (2)', function() {
       model.rows = [createRow({ height: 8 }, [[4], [2, 3], [4, 6], [2, 3], [2, 3], [8, 3]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 8, h: 8 },
         { x: 8, y: 0, w: 4, h: 3 },
         { x: 12, y: 0, w: 8, h: 6 },
@@ -294,9 +294,9 @@ describe('DashboardModel', function() {
 
     it('should fill current row if panel height more than row height', function() {
       model.rows = [createRow({ height: 6 }, [[4], [2, 3], [4, 8], [2, 3], [2, 3]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 8, h: 6 },
         { x: 8, y: 0, w: 4, h: 3 },
         { x: 12, y: 0, w: 8, h: 8 },
@@ -309,9 +309,9 @@ describe('DashboardModel', function() {
 
     it('should wrap panels to multiple rows', function() {
       model.rows = [createRow({ height: 6 }, [[6], [6], [12], [6], [3], [3]])];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 12, h: 6 },
         { x: 12, y: 0, w: 12, h: 6 },
         { x: 0, y: 6, w: 24, h: 6 },
@@ -328,9 +328,9 @@ describe('DashboardModel', function() {
         createRow({ showTitle: true, title: 'Row', height: 8, repeat: 'server' }, [[6]]),
         createRow({ height: 8 }, [[12]]),
       ];
-      let dashboard = new DashboardModel(model);
-      let panelGridPos = getGridPositions(dashboard);
-      let expectedGrid = [
+      const dashboard = new DashboardModel(model);
+      const panelGridPos = getGridPositions(dashboard);
+      const expectedGrid = [
         { x: 0, y: 0, w: 24, h: 8 },
         { x: 0, y: 1, w: 12, h: 8 },
         { x: 0, y: 9, w: 24, h: 8 },
@@ -359,7 +359,7 @@ describe('DashboardModel', function() {
         ),
       ];
 
-      let dashboard = new DashboardModel(model);
+      const dashboard = new DashboardModel(model);
       expect(dashboard.panels[0].repeat).toBe('server');
       expect(dashboard.panels.length).toBe(2);
     });
@@ -368,7 +368,7 @@ describe('DashboardModel', function() {
       model.rows = [createRow({ height: 8 }, [[6]])];
       model.rows[0].panels[0] = { minSpan: 12 };
 
-      let dashboard = new DashboardModel(model);
+      const dashboard = new DashboardModel(model);
       expect(dashboard.panels[0].minSpan).toBe(24);
     });
 
@@ -376,7 +376,7 @@ describe('DashboardModel', function() {
       model.rows = [createRow({ collapse: true, height: 8 }, [[6], [6]])];
       model.rows[0].panels[0] = {};
 
-      let dashboard = new DashboardModel(model);
+      const dashboard = new DashboardModel(model);
       expect(dashboard.panels[0].id).toBe(1);
     });
   });
@@ -386,15 +386,15 @@ function createRow(options, panelDescriptions: any[]) {
   const PANEL_HEIGHT_STEP = GRID_CELL_HEIGHT + GRID_CELL_VMARGIN;
   let { collapse, height, showTitle, title, repeat, repeatIteration } = options;
   height = height * PANEL_HEIGHT_STEP;
-  let panels = [];
+  const panels = [];
   _.each(panelDescriptions, panelDesc => {
-    let panel = { span: panelDesc[0] };
+    const panel = { span: panelDesc[0] };
     if (panelDesc.length > 1) {
       panel['height'] = panelDesc[1] * PANEL_HEIGHT_STEP;
     }
     panels.push(panel);
   });
-  let row = {
+  const row = {
     collapse,
     height,
     showTitle,
diff --git a/public/app/features/dashboard/specs/dashboard_model.test.ts b/public/app/features/dashboard/specs/dashboard_model.test.ts
index 6ac642cd58e..28029653a6c 100644
--- a/public/app/features/dashboard/specs/dashboard_model.test.ts
+++ b/public/app/features/dashboard/specs/dashboard_model.test.ts
@@ -457,16 +457,16 @@ describe('DashboardModel', function() {
     });
 
     it('getSaveModelClone should return original time when saveTimerange=false', () => {
-      let options = { saveTimerange: false };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveTimerange: false };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.time.from).toBe('now-6h');
       expect(saveModel.time.to).toBe('now');
     });
 
     it('getSaveModelClone should return updated time when saveTimerange=true', () => {
-      let options = { saveTimerange: true };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveTimerange: true };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.time.from).toBe('now-3h');
       expect(saveModel.time.to).toBe('now-1h');
@@ -478,16 +478,16 @@ describe('DashboardModel', function() {
     });
 
     it('getSaveModelClone should return original time when saveTimerange=false', () => {
-      let options = { saveTimerange: false };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveTimerange: false };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.time.from).toBe('now-6h');
       expect(saveModel.time.to).toBe('now');
     });
 
     it('getSaveModelClone should return updated time when saveTimerange=true', () => {
-      let options = { saveTimerange: true };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveTimerange: true };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.time.from).toBe('now-3h');
       expect(saveModel.time.to).toBe('now-1h');
@@ -542,8 +542,8 @@ describe('DashboardModel', function() {
     it('getSaveModelClone should return original variable when saveVariables=false', () => {
       model.templating.list[0].current.text = 'server_002';
 
-      let options = { saveVariables: false };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveVariables: false };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.templating.list[0].current.text).toBe('server_001');
     });
@@ -551,8 +551,8 @@ describe('DashboardModel', function() {
     it('getSaveModelClone should return updated variable when saveVariables=true', () => {
       model.templating.list[0].current.text = 'server_002';
 
-      let options = { saveVariables: true };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveVariables: true };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.templating.list[0].current.text).toBe('server_002');
     });
@@ -620,8 +620,8 @@ describe('DashboardModel', function() {
     it('getSaveModelClone should return original variable when saveVariables=false', () => {
       model.templating.list[0].filters[0].value = 'server 1';
 
-      let options = { saveVariables: false };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveVariables: false };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.templating.list[0].filters[0].value).toBe('server 20');
     });
@@ -629,8 +629,8 @@ describe('DashboardModel', function() {
     it('getSaveModelClone should return updated variable when saveVariables=true', () => {
       model.templating.list[0].filters[0].value = 'server 1';
 
-      let options = { saveVariables: true };
-      let saveModel = model.getSaveModelClone(options);
+      const options = { saveVariables: true };
+      const saveModel = model.getSaveModelClone(options);
 
       expect(saveModel.templating.list[0].filters[0].value).toBe('server 1');
     });
diff --git a/public/app/features/dashboard/specs/history_ctrl.test.ts b/public/app/features/dashboard/specs/history_ctrl.test.ts
index 991ecb2c60d..632f3489dae 100644
--- a/public/app/features/dashboard/specs/history_ctrl.test.ts
+++ b/public/app/features/dashboard/specs/history_ctrl.test.ts
@@ -70,7 +70,7 @@ describe('HistoryListCtrl', () => {
       });
 
       it('should add a checked property to each revision', () => {
-        let actual = _.filter(historyListCtrl.revisions, rev => rev.hasOwnProperty('checked'));
+        const actual = _.filter(historyListCtrl.revisions, rev => rev.hasOwnProperty('checked'));
         expect(actual.length).toBe(4);
       });
 
@@ -78,7 +78,7 @@ describe('HistoryListCtrl', () => {
         historyListCtrl.revisions[0].checked = true;
         historyListCtrl.revisions[2].checked = true;
         historyListCtrl.reset();
-        let actual = _.filter(historyListCtrl.revisions, rev => !rev.checked);
+        const actual = _.filter(historyListCtrl.revisions, rev => !rev.checked);
         expect(actual.length).toBe(4);
       });
     });
diff --git a/public/app/features/dashboard/specs/history_srv.test.ts b/public/app/features/dashboard/specs/history_srv.test.ts
index 401b098a0e1..5c8578ecf39 100644
--- a/public/app/features/dashboard/specs/history_srv.test.ts
+++ b/public/app/features/dashboard/specs/history_srv.test.ts
@@ -8,7 +8,7 @@ describe('historySrv', function() {
   const versionsResponse = versions();
   const restoreResponse = restore;
 
-  let backendSrv = {
+  const backendSrv = {
     get: jest.fn(() => Promise.resolve({})),
     post: jest.fn(() => Promise.resolve({})),
   };
@@ -44,7 +44,7 @@ describe('historySrv', function() {
 
   describe('restoreDashboard', () => {
     it('should return a success response given valid parameters', function() {
-      let version = 6;
+      const version = 6;
       backendSrv.post = jest.fn(() => Promise.resolve(restoreResponse(version)));
       historySrv = new HistorySrv(backendSrv);
       return historySrv.restoreDashboard(dash, version).then(function(response) {
@@ -54,7 +54,7 @@ describe('historySrv', function() {
 
     it('should return an empty object when not given an id', async () => {
       historySrv = new HistorySrv(backendSrv);
-      let rsp = await historySrv.restoreDashboard(emptyDash, 6);
+      const rsp = await historySrv.restoreDashboard(emptyDash, 6);
       expect(rsp).toEqual({});
     });
   });
diff --git a/public/app/features/dashboard/specs/repeat.test.ts b/public/app/features/dashboard/specs/repeat.test.ts
index 09bb3b7c494..d8c9e3bc2ed 100644
--- a/public/app/features/dashboard/specs/repeat.test.ts
+++ b/public/app/features/dashboard/specs/repeat.test.ts
@@ -8,7 +8,7 @@ describe('given dashboard with panel repeat', function() {
   var dashboard;
 
   beforeEach(function() {
-    let dashboardJSON = {
+    const dashboardJSON = {
       panels: [
         { id: 1, type: 'row', gridPos: { x: 0, y: 0, h: 1, w: 24 } },
         { id: 2, repeat: 'apps', repeatDirection: 'h', gridPos: { x: 0, y: 1, h: 2, w: 8 } },
diff --git a/public/app/features/dashboard/specs/viewstate_srv.test.ts b/public/app/features/dashboard/specs/viewstate_srv.test.ts
index 08166c6f2bd..740e3c3b9a8 100644
--- a/public/app/features/dashboard/specs/viewstate_srv.test.ts
+++ b/public/app/features/dashboard/specs/viewstate_srv.test.ts
@@ -4,12 +4,12 @@ import config from 'app/core/config';
 import { DashboardViewState } from '../view_state_srv';
 
 describe('when updating view state', () => {
-  let location = {
+  const location = {
     replace: jest.fn(),
     search: jest.fn(),
   };
 
-  let $scope = {
+  const $scope = {
     onAppEvent: jest.fn(() => {}),
     dashboard: {
       meta: {},
@@ -17,7 +17,7 @@ describe('when updating view state', () => {
     },
   };
 
-  let $rootScope = {};
+  const $rootScope = {};
   let viewState;
 
   beforeEach(() => {
diff --git a/public/app/features/dashboard/validation_srv.ts b/public/app/features/dashboard/validation_srv.ts
index 817be7ca0e3..3e8306039d7 100644
--- a/public/app/features/dashboard/validation_srv.ts
+++ b/public/app/features/dashboard/validation_srv.ts
@@ -37,7 +37,7 @@ export class ValidationSrv {
       });
     }
 
-    let deferred = this.$q.defer();
+    const deferred = this.$q.defer();
 
     const promises = [];
     promises.push(this.backendSrv.search({ type: hitTypes.FOLDER, folderIds: [folderId], query: name }));
@@ -54,7 +54,7 @@ export class ValidationSrv {
         hits = hits.concat(res[1]);
       }
 
-      for (let hit of hits) {
+      for (const hit of hits) {
         if (nameLowerCased === hit.title.toLowerCase()) {
           deferred.reject({
             type: 'EXISTING',
diff --git a/public/app/features/dashboard/view_state_srv.ts b/public/app/features/dashboard/view_state_srv.ts
index 1ed2d61df71..5bd4db6fddc 100644
--- a/public/app/features/dashboard/view_state_srv.ts
+++ b/public/app/features/dashboard/view_state_srv.ts
@@ -111,9 +111,9 @@ export class DashboardViewState {
   }
 
   toggleCollapsedPanelRow(panelId) {
-    for (let panel of this.dashboard.panels) {
+    for (const panel of this.dashboard.panels) {
       if (panel.collapsed) {
-        for (let rowPanel of panel.panels) {
+        for (const rowPanel of panel.panels) {
           if (rowPanel.id === panelId) {
             this.dashboard.toggleRow(panel);
             return;
diff --git a/public/app/features/org/org_users_ctrl.ts b/public/app/features/org/org_users_ctrl.ts
index d35b967626a..625e2749399 100644
--- a/public/app/features/org/org_users_ctrl.ts
+++ b/public/app/features/org/org_users_ctrl.ts
@@ -44,7 +44,7 @@ export class OrgUsersCtrl {
   }
 
   onQueryUpdated() {
-    let regex = new RegExp(this.searchQuery, 'ig');
+    const regex = new RegExp(this.searchQuery, 'ig');
     this.users = _.filter(this.unfiltered, item => {
       return regex.test(item.email) || regex.test(item.login);
     });
diff --git a/public/app/features/panel/metrics_tab.ts b/public/app/features/panel/metrics_tab.ts
index 4da40f214a1..94aa142a6b8 100644
--- a/public/app/features/panel/metrics_tab.ts
+++ b/public/app/features/panel/metrics_tab.ts
@@ -28,7 +28,7 @@ export class MetricsTabCtrl {
     this.datasources = datasourceSrv.getMetricSources();
     this.panelDsValue = this.panelCtrl.panel.datasource;
 
-    for (let ds of this.datasources) {
+    for (const ds of this.datasources) {
       if (ds.value === this.panelDsValue) {
         this.datasourceInstance = ds;
       }
diff --git a/public/app/features/panel/panel_ctrl.ts b/public/app/features/panel/panel_ctrl.ts
index 6402227164f..6a583b700ef 100644
--- a/public/app/features/panel/panel_ctrl.ts
+++ b/public/app/features/panel/panel_ctrl.ts
@@ -138,7 +138,7 @@ export class PanelCtrl {
   }
 
   getMenu() {
-    let menu = [];
+    const menu = [];
     menu.push({
       text: 'View',
       click: 'ctrl.viewPanel();',
@@ -166,7 +166,7 @@ export class PanelCtrl {
     // Additional items from sub-class
     menu.push(...this.getAdditionalMenuItems());
 
-    let extendedMenu = this.getExtendedMenu();
+    const extendedMenu = this.getExtendedMenu();
     menu.push({
       text: 'More ...',
       click: '',
@@ -189,7 +189,7 @@ export class PanelCtrl {
   }
 
   getExtendedMenu() {
-    let menu = [];
+    const menu = [];
     if (!this.fullscreen && this.dashboard.meta.canEdit) {
       menu.push({
         text: 'Duplicate',
@@ -259,7 +259,7 @@ export class PanelCtrl {
   }
 
   editPanelJson() {
-    let editScope = this.$scope.$root.$new();
+    const editScope = this.$scope.$root.$new();
     editScope.object = this.panel.getSaveModel();
     editScope.updateHandler = this.replacePanel.bind(this);
     editScope.enableCopy = true;
@@ -276,12 +276,12 @@ export class PanelCtrl {
   }
 
   replacePanel(newPanel, oldPanel) {
-    let dashboard = this.dashboard;
-    let index = _.findIndex(dashboard.panels, panel => {
+    const dashboard = this.dashboard;
+    const index = _.findIndex(dashboard.panels, panel => {
       return panel.id === oldPanel.id;
     });
 
-    let deletedPanel = dashboard.panels.splice(index, 1);
+    const deletedPanel = dashboard.panels.splice(index, 1);
     this.dashboard.events.emit('panel-removed', deletedPanel);
 
     newPanel = new PanelModel(newPanel);
@@ -333,7 +333,7 @@ export class PanelCtrl {
 
     if (this.panel.links && this.panel.links.length > 0) {
       html += '<ul>';
-      for (let link of this.panel.links) {
+      for (const link of this.panel.links) {
         var info = linkSrv.getPanelLinkAnchorInfo(link, this.panel.scopedVars);
         html +=
           '<li><a class="panel-menu-link" href="' +
diff --git a/public/app/features/panel/panel_directive.ts b/public/app/features/panel/panel_directive.ts
index e549ca262d3..ff5d045a1de 100644
--- a/public/app/features/panel/panel_directive.ts
+++ b/public/app/features/panel/panel_directive.ts
@@ -112,8 +112,8 @@ module.directive('grafanaPanel', function($rootScope, $document, $timeout) {
             </div>
           `;
 
-          let scrollRoot = panelContent;
-          let scroller = panelContent.find(':first').find(':first');
+          const scrollRoot = panelContent;
+          const scroller = panelContent.find(':first').find(':first');
 
           scrollRoot.addClass(scrollRootClass);
           $(scrollBarHTML).appendTo(scrollRoot);
diff --git a/public/app/features/panel/panel_header.ts b/public/app/features/panel/panel_header.ts
index 1e2bc241d63..aeb69c57713 100644
--- a/public/app/features/panel/panel_header.ts
+++ b/public/app/features/panel/panel_header.ts
@@ -60,7 +60,7 @@ function renderMenuItem(item, ctrl) {
 
   if (item.submenu) {
     html += '<ul class="dropdown-menu dropdown-menu--menu panel-menu">';
-    for (let subitem of item.submenu) {
+    for (const subitem of item.submenu) {
       html += renderMenuItem(subitem, ctrl);
     }
     html += '</ul>';
@@ -73,7 +73,7 @@ function renderMenuItem(item, ctrl) {
 function createMenuTemplate(ctrl) {
   let html = '';
 
-  for (let item of ctrl.getMenu()) {
+  for (const item of ctrl.getMenu()) {
     html += renderMenuItem(item, ctrl);
   }
 
@@ -86,7 +86,7 @@ function panelHeader($compile) {
     restrict: 'E',
     template: template,
     link: function(scope, elem, attrs) {
-      let menuElem = elem.find('.panel-menu');
+      const menuElem = elem.find('.panel-menu');
       let menuScope;
       let isDragged;
 
@@ -99,7 +99,7 @@ function panelHeader($compile) {
         }
 
         menuScope = scope.$new();
-        let menuHtml = createMenuTemplate(scope.ctrl);
+        const menuHtml = createMenuTemplate(scope.ctrl);
         menuElem.html(menuHtml);
         $compile(menuElem)(menuScope);
 
@@ -132,12 +132,12 @@ function panelHeader($compile) {
           .find('[data-toggle=dropdown]')
           .parentsUntil('.panel')
           .parent();
-        let menuElem = elem.find('[data-toggle=dropdown]').parent();
+        const menuElem = elem.find('[data-toggle=dropdown]').parent();
         panelElem = panelElem && panelElem.length ? panelElem[0] : undefined;
         if (panelElem) {
           panelElem = $(panelElem);
           $(panelGridClass).removeClass(menuOpenClass);
-          let state = !menuElem.hasClass('open');
+          const state = !menuElem.hasClass('open');
           panelElem.toggleClass(menuOpenClass, state);
         }
       }
diff --git a/public/app/features/panel/solo_panel_ctrl.ts b/public/app/features/panel/solo_panel_ctrl.ts
index 242d2e7da3e..85773a3a778 100644
--- a/public/app/features/panel/solo_panel_ctrl.ts
+++ b/public/app/features/panel/solo_panel_ctrl.ts
@@ -34,7 +34,7 @@ export class SoloPanelCtrl {
     };
 
     $scope.initPanelScope = function() {
-      let panelInfo = $scope.dashboard.getPanelInfoById(panelId);
+      const panelInfo = $scope.dashboard.getPanelInfoById(panelId);
 
       // fake row ctrl scope
       $scope.ctrl = {
diff --git a/public/app/features/panellinks/specs/link_srv.test.ts b/public/app/features/panellinks/specs/link_srv.test.ts
index 2ec38961e29..521a4edef15 100644
--- a/public/app/features/panellinks/specs/link_srv.test.ts
+++ b/public/app/features/panellinks/specs/link_srv.test.ts
@@ -2,7 +2,7 @@ import { LinkSrv } from '../link_srv';
 import _ from 'lodash';
 
 jest.mock('angular', () => {
-  let AngularJSMock = require('test/mocks/angular');
+  const AngularJSMock = require('test/mocks/angular');
   return new AngularJSMock();
 });
 
diff --git a/public/app/features/playlist/playlist_routes.ts b/public/app/features/playlist/playlist_routes.ts
index b898820e371..3cb9aceaefb 100644
--- a/public/app/features/playlist/playlist_routes.ts
+++ b/public/app/features/playlist/playlist_routes.ts
@@ -24,7 +24,7 @@ function grafanaRoutes($routeProvider) {
       controller: 'PlaylistsCtrl',
       resolve: {
         init: function(playlistSrv, $route) {
-          let playlistId = $route.current.params.id;
+          const playlistId = $route.current.params.id;
           playlistSrv.start(playlistId);
         },
       },
diff --git a/public/app/features/playlist/specs/playlist_edit_ctrl.test.ts b/public/app/features/playlist/specs/playlist_edit_ctrl.test.ts
index f313c6e8e6a..183947f5072 100644
--- a/public/app/features/playlist/specs/playlist_edit_ctrl.test.ts
+++ b/public/app/features/playlist/specs/playlist_edit_ctrl.test.ts
@@ -4,7 +4,7 @@ import { PlaylistEditCtrl } from '../playlist_edit_ctrl';
 describe('PlaylistEditCtrl', () => {
   var ctx: any;
   beforeEach(() => {
-    let navModelSrv = {
+    const navModelSrv = {
       getNav: () => {
         return { breadcrumbs: [], node: {} };
       },
diff --git a/public/app/features/plugins/ds_list_ctrl.ts b/public/app/features/plugins/ds_list_ctrl.ts
index 89c760ae253..71c1a516842 100644
--- a/public/app/features/plugins/ds_list_ctrl.ts
+++ b/public/app/features/plugins/ds_list_ctrl.ts
@@ -17,7 +17,7 @@ export class DataSourcesCtrl {
   }
 
   onQueryUpdated() {
-    let regex = new RegExp(this.searchQuery, 'ig');
+    const regex = new RegExp(this.searchQuery, 'ig');
     this.datasources = _.filter(this.unfiltered, item => {
       regex.lastIndex = 0;
       return regex.test(item.name) || regex.test(item.type);
diff --git a/public/app/features/plugins/plugin_component.ts b/public/app/features/plugins/plugin_component.ts
index 1936e57f558..bdfb47bc861 100644
--- a/public/app/features/plugins/plugin_component.ts
+++ b/public/app/features/plugins/plugin_component.ts
@@ -68,7 +68,7 @@ function pluginDirectiveLoader($compile, datasourceSrv, $rootScope, $q, $http, $
       },
     };
 
-    let panelInfo = config.panels[scope.panel.type];
+    const panelInfo = config.panels[scope.panel.type];
     var panelCtrlPromise = Promise.resolve(UnknownPanelCtrl);
     if (panelInfo) {
       panelCtrlPromise = importPluginModule(panelInfo.module).then(function(panelModule) {
@@ -107,7 +107,7 @@ function pluginDirectiveLoader($compile, datasourceSrv, $rootScope, $q, $http, $
     switch (attrs.type) {
       // QueryCtrl
       case 'query-ctrl': {
-        let datasource = scope.target.datasource || scope.ctrl.panel.datasource;
+        const datasource = scope.target.datasource || scope.ctrl.panel.datasource;
         return datasourceSrv.get(datasource).then(ds => {
           scope.datasource = ds;
 
@@ -160,7 +160,7 @@ function pluginDirectiveLoader($compile, datasourceSrv, $rootScope, $q, $http, $
       }
       // AppConfigCtrl
       case 'app-config-ctrl': {
-        let model = scope.ctrl.model;
+        const model = scope.ctrl.model;
         return importPluginModule(model.module).then(function(appModule) {
           return {
             baseUrl: model.baseUrl,
@@ -173,7 +173,7 @@ function pluginDirectiveLoader($compile, datasourceSrv, $rootScope, $q, $http, $
       }
       // App Page
       case 'app-page': {
-        let appModel = scope.ctrl.appModel;
+        const appModel = scope.ctrl.appModel;
         return importPluginModule(appModel.module).then(function(appModule) {
           return {
             baseUrl: appModel.baseUrl,
diff --git a/public/app/features/plugins/plugin_edit_ctrl.ts b/public/app/features/plugins/plugin_edit_ctrl.ts
index 6aa8b2bc38f..93c2008651d 100644
--- a/public/app/features/plugins/plugin_edit_ctrl.ts
+++ b/public/app/features/plugins/plugin_edit_ctrl.ts
@@ -53,7 +53,7 @@ export class PluginEditCtrl {
         url: `plugins/${this.model.id}/edit?tab=config`,
       });
 
-      let hasDashboards = _.find(model.includes, { type: 'dashboard' });
+      const hasDashboards = _.find(model.includes, { type: 'dashboard' });
 
       if (hasDashboards) {
         this.navModel.main.children.push({
@@ -69,7 +69,7 @@ export class PluginEditCtrl {
 
     this.tab = this.$routeParams.tab || defaultTab;
 
-    for (let tab of this.navModel.main.children) {
+    for (const tab of this.navModel.main.children) {
       if (tab.id === this.tab) {
         tab.active = true;
       }
@@ -98,7 +98,7 @@ export class PluginEditCtrl {
   initReadme() {
     return this.backendSrv.get(`/api/plugins/${this.pluginId}/markdown/readme`).then(res => {
       var md = new Remarkable({
-        linkify: true
+        linkify: true,
       });
       this.readmeHtml = this.$sce.trustAsHtml(md.render(res));
     });
diff --git a/public/app/features/plugins/plugin_list_ctrl.ts b/public/app/features/plugins/plugin_list_ctrl.ts
index 8e303143946..315252364cc 100644
--- a/public/app/features/plugins/plugin_list_ctrl.ts
+++ b/public/app/features/plugins/plugin_list_ctrl.ts
@@ -20,7 +20,7 @@ export class PluginListCtrl {
   }
 
   onQueryUpdated() {
-    let regex = new RegExp(this.searchQuery, 'ig');
+    const regex = new RegExp(this.searchQuery, 'ig');
     this.plugins = _.filter(this.allPlugins, item => {
       return regex.test(item.name) || regex.test(item.type);
     });
diff --git a/public/app/features/plugins/plugin_loader.ts b/public/app/features/plugins/plugin_loader.ts
index cce494d0a60..e227dbb910c 100644
--- a/public/app/features/plugins/plugin_loader.ts
+++ b/public/app/features/plugins/plugin_loader.ts
@@ -140,12 +140,12 @@ const flotDeps = [
   'jquery.flot.events',
   'jquery.flot.gauge',
 ];
-for (let flotDep of flotDeps) {
+for (const flotDep of flotDeps) {
   exposeToPlugin(flotDep, { fakeDep: 1 });
 }
 
 export function importPluginModule(path: string): Promise<any> {
-  let builtIn = builtInPlugins[path];
+  const builtIn = builtInPlugins[path];
   if (builtIn) {
     return Promise.resolve(builtIn);
   }
diff --git a/public/app/features/plugins/plugin_page_ctrl.ts b/public/app/features/plugins/plugin_page_ctrl.ts
index 397916aacc8..a2920e55a2a 100644
--- a/public/app/features/plugins/plugin_page_ctrl.ts
+++ b/public/app/features/plugins/plugin_page_ctrl.ts
@@ -33,7 +33,7 @@ export class AppPageCtrl {
       return;
     }
 
-    let pluginNav = this.navModelSrv.getNav('plugin-page-' + app.id);
+    const pluginNav = this.navModelSrv.getNav('plugin-page-' + app.id);
 
     this.navModel = {
       main: {
diff --git a/public/app/features/plugins/specs/datasource_srv.test.ts b/public/app/features/plugins/specs/datasource_srv.test.ts
index b63e8537837..653e431cb9f 100644
--- a/public/app/features/plugins/specs/datasource_srv.test.ts
+++ b/public/app/features/plugins/specs/datasource_srv.test.ts
@@ -16,7 +16,7 @@ const templateSrv = {
 };
 
 describe('datasource_srv', function() {
-  let _datasourceSrv = new DatasourceSrv({}, {}, {}, templateSrv);
+  const _datasourceSrv = new DatasourceSrv({}, {}, {}, templateSrv);
 
   describe('when loading explore sources', () => {
     beforeEach(() => {
@@ -46,7 +46,7 @@ describe('datasource_srv', function() {
 
   describe('when loading metric sources', () => {
     let metricSources;
-    let unsortedDatasources = {
+    const unsortedDatasources = {
       mmm: {
         type: 'test-db',
         meta: { metrics: { m: 1 } },
diff --git a/public/app/features/templating/specs/editor_ctrl.test.ts b/public/app/features/templating/specs/editor_ctrl.test.ts
index f49d0ccd9c6..bba175c2d86 100644
--- a/public/app/features/templating/specs/editor_ctrl.test.ts
+++ b/public/app/features/templating/specs/editor_ctrl.test.ts
@@ -9,7 +9,7 @@ jest.mock('app/core/app_events', () => {
 });
 
 describe('VariableEditorCtrl', () => {
-  let scope = {
+  const scope = {
     runQuery: () => {
       return Promise.resolve({});
     },
diff --git a/public/app/features/templating/specs/variable_srv_init.test.ts b/public/app/features/templating/specs/variable_srv_init.test.ts
index ea8689f528b..e011d4d0d15 100644
--- a/public/app/features/templating/specs/variable_srv_init.test.ts
+++ b/public/app/features/templating/specs/variable_srv_init.test.ts
@@ -5,7 +5,7 @@ import { VariableSrv } from '../variable_srv';
 import $q from 'q';
 
 describe('VariableSrv init', function() {
-  let templateSrv = {
+  const templateSrv = {
     init: vars => {
       this.variables = vars;
     },
@@ -17,8 +17,8 @@ describe('VariableSrv init', function() {
       }),
   };
 
-  let $injector = <any>{};
-  let $rootscope = {
+  const $injector = <any>{};
+  const $rootscope = {
     $on: () => {},
   };
 
diff --git a/public/app/features/templating/variable_srv.ts b/public/app/features/templating/variable_srv.ts
index bd214639552..e3e75d6a036 100644
--- a/public/app/features/templating/variable_srv.ts
+++ b/public/app/features/templating/variable_srv.ts
@@ -23,7 +23,7 @@ export class VariableSrv {
     this.templateSrv.init(this.variables);
 
     // init variables
-    for (let variable of this.variables) {
+    for (const variable of this.variables) {
       variable.initLock = this.$q.defer();
     }
 
@@ -60,7 +60,7 @@ export class VariableSrv {
   processVariable(variable, queryParams) {
     var dependencies = [];
 
-    for (let otherVariable of this.variables) {
+    for (const otherVariable of this.variables) {
       if (variable.dependsOn(otherVariable)) {
         dependencies.push(otherVariable.initLock.promise);
       }
@@ -212,13 +212,13 @@ export class VariableSrv {
       });
 
       let defaultText = urlValue;
-      let defaultValue = urlValue;
+      const defaultValue = urlValue;
 
       if (!option && _.isArray(urlValue)) {
         defaultText = [];
 
         for (let n = 0; n < urlValue.length; n++) {
-          let t = _.find(variable.options, op => {
+          const t = _.find(variable.options, op => {
             return op.value === urlValue[n];
           });
 
@@ -275,7 +275,7 @@ export class VariableSrv {
       this.addVariable(variable);
     }
 
-    let filters = variable.filters;
+    const filters = variable.filters;
     let filter = _.find(filters, { key: options.key, value: options.value });
 
     if (!filter) {
@@ -288,7 +288,7 @@ export class VariableSrv {
   }
 
   createGraph() {
-    let g = new Graph();
+    const g = new Graph();
 
     this.variables.forEach(v1 => {
       g.createNode(v1.name);
diff --git a/public/app/plugins/datasource/cloudwatch/datasource.ts b/public/app/plugins/datasource/cloudwatch/datasource.ts
index 087bd19da71..63a35e72add 100644
--- a/public/app/plugins/datasource/cloudwatch/datasource.ts
+++ b/public/app/plugins/datasource/cloudwatch/datasource.ts
@@ -45,7 +45,7 @@ export default class CloudWatchDatasource {
       item.returnData = typeof item.hide === 'undefined' ? true : !item.hide;
 
       // valid ExtendedStatistics is like p90.00, check the pattern
-      let hasInvalidStatistics = item.statistics.some(s => {
+      const hasInvalidStatistics = item.statistics.some(s => {
         return s.indexOf('p') === 0 && !/p\d{2}\.\d{2}/.test(s);
       });
       if (hasInvalidStatistics) {
@@ -402,7 +402,7 @@ export default class CloudWatchDatasource {
             value: v,
           };
         });
-    let useSelectedVariables =
+    const useSelectedVariables =
       selectedVariables.some(s => {
         return s.value === currentVariables[0].value;
       }) || currentVariables[0].value === '$__all';
diff --git a/public/app/plugins/datasource/cloudwatch/specs/datasource.test.ts b/public/app/plugins/datasource/cloudwatch/specs/datasource.test.ts
index a8968008661..eae3e91d37d 100644
--- a/public/app/plugins/datasource/cloudwatch/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/cloudwatch/specs/datasource.test.ts
@@ -4,18 +4,18 @@ import * as dateMath from 'app/core/utils/datemath';
 import _ from 'lodash';
 
 describe('CloudWatchDatasource', function() {
-  let instanceSettings = {
+  const instanceSettings = {
     jsonData: { defaultRegion: 'us-east-1', access: 'proxy' },
   };
 
-  let templateSrv = {
+  const templateSrv = {
     data: {},
     templateSettings: { interpolate: /\[\[([\s\S]+?)\]\]/g },
     replace: text => _.template(text, templateSrv.templateSettings)(templateSrv.data),
     variableExists: () => false,
   };
 
-  let timeSrv = {
+  const timeSrv = {
     time: { from: 'now-1h', to: 'now' },
     timeRange: () => {
       return {
@@ -24,8 +24,8 @@ describe('CloudWatchDatasource', function() {
       };
     },
   };
-  let backendSrv = {};
-  let ctx = <any>{
+  const backendSrv = {};
+  const ctx = <any>{
     backendSrv,
     templateSrv,
   };
@@ -121,7 +121,7 @@ describe('CloudWatchDatasource', function() {
       });
     });
 
-    it('should cancel query for invalid extended statistics', function () {
+    it('should cancel query for invalid extended statistics', function() {
       var query = {
         range: { from: 'now-1h', to: 'now' },
         rangeRaw: { from: 1483228800, to: 1483232400 },
@@ -252,7 +252,7 @@ describe('CloudWatchDatasource', function() {
 
   function describeMetricFindQuery(query, func) {
     describe('metricFindQuery ' + query, () => {
-      let scenario: any = {};
+      const scenario: any = {};
       scenario.setup = setupCallback => {
         beforeEach(() => {
           setupCallback();
@@ -461,12 +461,12 @@ describe('CloudWatchDatasource', function() {
         3600,
       ],
     ];
-    for (let t of testData) {
-      let target = t[0];
-      let options = t[1];
-      let now = new Date(options.range.from.valueOf() + t[2] * 1000);
-      let expected = t[3];
-      let actual = ctx.ds.getPeriod(target, options, now);
+    for (const t of testData) {
+      const target = t[0];
+      const options = t[1];
+      const now = new Date(options.range.from.valueOf() + t[2] * 1000);
+      const expected = t[3];
+      const actual = ctx.ds.getPeriod(target, options, now);
       expect(actual).toBe(expected);
     }
   });
diff --git a/public/app/plugins/datasource/elasticsearch/datasource.ts b/public/app/plugins/datasource/elasticsearch/datasource.ts
index 5a8e83a16cb..b77ebe6b738 100644
--- a/public/app/plugins/datasource/elasticsearch/datasource.ts
+++ b/public/app/plugins/datasource/elasticsearch/datasource.ts
@@ -414,13 +414,13 @@ export class ElasticDatasource {
       return true;
     }
 
-    for (let bucketAgg of target.bucketAggs) {
+    for (const bucketAgg of target.bucketAggs) {
       if (this.templateSrv.variableExists(bucketAgg.field) || this.objectContainsTemplate(bucketAgg.settings)) {
         return true;
       }
     }
 
-    for (let metric of target.metrics) {
+    for (const metric of target.metrics) {
       if (
         this.templateSrv.variableExists(metric.field) ||
         this.objectContainsTemplate(metric.settings) ||
@@ -449,13 +449,13 @@ export class ElasticDatasource {
       return false;
     }
 
-    for (let key of Object.keys(obj)) {
+    for (const key of Object.keys(obj)) {
       if (this.isPrimitive(obj[key])) {
         if (this.templateSrv.variableExists(obj[key])) {
           return true;
         }
       } else if (Array.isArray(obj[key])) {
-        for (let item of obj[key]) {
+        for (const item of obj[key]) {
           if (this.objectContainsTemplate(item)) {
             return true;
           }
diff --git a/public/app/plugins/datasource/elasticsearch/elastic_response.ts b/public/app/plugins/datasource/elasticsearch/elastic_response.ts
index a378ab8b55f..e792d290d5b 100644
--- a/public/app/plugins/datasource/elasticsearch/elastic_response.ts
+++ b/public/app/plugins/datasource/elasticsearch/elastic_response.ts
@@ -112,29 +112,29 @@ export class ElasticResponse {
   processAggregationDocs(esAgg, aggDef, target, table, props) {
     // add columns
     if (table.columns.length === 0) {
-      for (let propKey of _.keys(props)) {
+      for (const propKey of _.keys(props)) {
         table.addColumn({ text: propKey, filterable: true });
       }
       table.addColumn({ text: aggDef.field, filterable: true });
     }
 
     // helper func to add values to value array
-    let addMetricValue = (values, metricName, value) => {
+    const addMetricValue = (values, metricName, value) => {
       table.addColumn({ text: metricName });
       values.push(value);
     };
 
-    for (let bucket of esAgg.buckets) {
-      let values = [];
+    for (const bucket of esAgg.buckets) {
+      const values = [];
 
-      for (let propValues of _.values(props)) {
+      for (const propValues of _.values(props)) {
         values.push(propValues);
       }
 
       // add bucket key (value)
       values.push(bucket.key);
 
-      for (let metric of target.metrics) {
+      for (const metric of target.metrics) {
         switch (metric.type) {
           case 'count': {
             addMetricValue(values, this.getMetricName(metric.type), bucket.doc_count);
@@ -157,7 +157,7 @@ export class ElasticResponse {
           }
           default: {
             let metricName = this.getMetricName(metric.type);
-            let otherMetrics = _.filter(target.metrics, { type: metric.type });
+            const otherMetrics = _.filter(target.metrics, { type: metric.type });
 
             // if more of the same metric type include field field name in property
             if (otherMetrics.length > 1) {
diff --git a/public/app/plugins/datasource/elasticsearch/specs/datasource.test.ts b/public/app/plugins/datasource/elasticsearch/specs/datasource.test.ts
index 36e7a63a005..d1e2e3ba835 100644
--- a/public/app/plugins/datasource/elasticsearch/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/elasticsearch/specs/datasource.test.ts
@@ -6,21 +6,21 @@ import { ElasticDatasource } from '../datasource';
 import * as dateMath from 'app/core/utils/datemath';
 
 describe('ElasticDatasource', function() {
-  let backendSrv = {
+  const backendSrv = {
     datasourceRequest: jest.fn(),
   };
 
-  let $rootScope = {
+  const $rootScope = {
     $on: jest.fn(),
     appEvent: jest.fn(),
   };
 
-  let templateSrv = {
+  const templateSrv = {
     replace: jest.fn(text => text),
     getAdhocFilters: jest.fn(() => []),
   };
 
-  let timeSrv = {
+  const timeSrv = {
     time: { from: 'now-1h', to: 'now' },
     timeRange: jest.fn(() => {
       return {
@@ -33,7 +33,7 @@ describe('ElasticDatasource', function() {
     }),
   };
 
-  let ctx = <any>{
+  const ctx = <any>{
     $rootScope,
     backendSrv,
   };
diff --git a/public/app/plugins/datasource/grafana/datasource.ts b/public/app/plugins/datasource/grafana/datasource.ts
index 9fa32fa6503..c3687161414 100644
--- a/public/app/plugins/datasource/grafana/datasource.ts
+++ b/public/app/plugins/datasource/grafana/datasource.ts
@@ -17,7 +17,7 @@ class GrafanaDatasource {
 
         if (res.results) {
           _.forEach(res.results, queryRes => {
-            for (let series of queryRes.series) {
+            for (const series of queryRes.series) {
               data.push({
                 target: series.name,
                 datapoints: series.points,
diff --git a/public/app/plugins/datasource/graphite/datasource.ts b/public/app/plugins/datasource/graphite/datasource.ts
index bc1c5722c3f..d4bdabd1f56 100644
--- a/public/app/plugins/datasource/graphite/datasource.ts
+++ b/public/app/plugins/datasource/graphite/datasource.ts
@@ -210,8 +210,8 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.metricFindQuery = function(query, optionalOptions) {
-    let options = optionalOptions || {};
-    let interpolatedQuery = templateSrv.replace(query);
+    const options = optionalOptions || {};
+    const interpolatedQuery = templateSrv.replace(query);
 
     // special handling for tag_values(<tag>[,<expression>]*), this is used for template variables
     let matches = interpolatedQuery.match(/^tag_values\(([^,]+)((, *[^,]+)*)\)$/);
@@ -242,7 +242,7 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
       return this.getTagsAutoComplete(expressions, undefined, options);
     }
 
-    let httpOptions: any = {
+    const httpOptions: any = {
       method: 'GET',
       url: '/metrics/find',
       params: {
@@ -268,9 +268,9 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.getTags = function(optionalOptions) {
-    let options = optionalOptions || {};
+    const options = optionalOptions || {};
 
-    let httpOptions: any = {
+    const httpOptions: any = {
       method: 'GET',
       url: '/tags',
       // for cancellations
@@ -293,9 +293,9 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.getTagValues = function(tag, optionalOptions) {
-    let options = optionalOptions || {};
+    const options = optionalOptions || {};
 
-    let httpOptions: any = {
+    const httpOptions: any = {
       method: 'GET',
       url: '/tags/' + templateSrv.replace(tag),
       // for cancellations
@@ -322,9 +322,9 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.getTagsAutoComplete = (expressions, tagPrefix, optionalOptions) => {
-    let options = optionalOptions || {};
+    const options = optionalOptions || {};
 
-    let httpOptions: any = {
+    const httpOptions: any = {
       method: 'GET',
       url: '/tags/autoComplete/tags',
       params: {
@@ -357,9 +357,9 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.getTagValuesAutoComplete = (expressions, tag, valuePrefix, optionalOptions) => {
-    let options = optionalOptions || {};
+    const options = optionalOptions || {};
 
-    let httpOptions: any = {
+    const httpOptions: any = {
       method: 'GET',
       url: '/tags/autoComplete/values',
       params: {
@@ -393,9 +393,9 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.getVersion = function(optionalOptions) {
-    let options = optionalOptions || {};
+    const options = optionalOptions || {};
 
-    let httpOptions = {
+    const httpOptions = {
       method: 'GET',
       url: '/version',
       requestId: options.requestId,
@@ -404,7 +404,7 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
     return this.doGraphiteRequest(httpOptions)
       .then(results => {
         if (results.data) {
-          let semver = new SemVersion(results.data);
+          const semver = new SemVersion(results.data);
           return semver.isValid() ? results.data : '';
         }
         return '';
@@ -437,7 +437,7 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
       return this.funcDefsPromise;
     }
 
-    let httpOptions = {
+    const httpOptions = {
       method: 'GET',
       url: '/functions',
     };
@@ -461,7 +461,7 @@ export function GraphiteDatasource(instanceSettings, $q, backendSrv, templateSrv
   };
 
   this.testDatasource = function() {
-    let query = {
+    const query = {
       panelId: 3,
       rangeRaw: { from: 'now-1h', to: 'now' },
       targets: [{ target: 'constantLine(100)' }],
diff --git a/public/app/plugins/datasource/graphite/graphite_query.ts b/public/app/plugins/datasource/graphite/graphite_query.ts
index baa58237708..7563a42f583 100644
--- a/public/app/plugins/datasource/graphite/graphite_query.ts
+++ b/public/app/plugins/datasource/graphite/graphite_query.ts
@@ -59,11 +59,11 @@ export default class GraphiteQuery {
   }
 
   checkForSeriesByTag() {
-    let seriesByTagFunc = _.find(this.functions, func => func.def.name === 'seriesByTag');
+    const seriesByTagFunc = _.find(this.functions, func => func.def.name === 'seriesByTag');
     if (seriesByTagFunc) {
       this.seriesByTagUsed = true;
       seriesByTagFunc.hidden = true;
-      let tags = this.splitSeriesByTagParams(seriesByTagFunc);
+      const tags = this.splitSeriesByTagParams(seriesByTagFunc);
       this.tags = tags;
     }
   }
@@ -186,8 +186,8 @@ export default class GraphiteQuery {
       let refCount = 0;
       _.each(targetsByRefId, (t, id) => {
         if (id !== refId) {
-          let match = nestedSeriesRefRegex.exec(t.target);
-          let count = match && match.length ? match.length - 1 : 0;
+          const match = nestedSeriesRefRegex.exec(t.target);
+          const count = match && match.length ? match.length - 1 : 0;
           refCount += count;
         }
       });
@@ -232,9 +232,9 @@ export default class GraphiteQuery {
     const tagPattern = /([^\!=~]+)(\!?=~?)(.*)/;
     return _.flatten(
       _.map(func.params, (param: string) => {
-        let matches = tagPattern.exec(param);
+        const matches = tagPattern.exec(param);
         if (matches) {
-          let tag = matches.slice(1);
+          const tag = matches.slice(1);
           if (tag.length === 3) {
             return {
               key: tag[0],
@@ -253,7 +253,7 @@ export default class GraphiteQuery {
   }
 
   getSeriesByTagFunc() {
-    let seriesByTagFuncIndex = this.getSeriesByTagFuncIndex();
+    const seriesByTagFuncIndex = this.getSeriesByTagFuncIndex();
     if (seriesByTagFuncIndex >= 0) {
       return this.functions[seriesByTagFuncIndex];
     } else {
@@ -262,7 +262,7 @@ export default class GraphiteQuery {
   }
 
   addTag(tag) {
-    let newTagParam = renderTagString(tag);
+    const newTagParam = renderTagString(tag);
     this.getSeriesByTagFunc().params.push(newTagParam);
     this.tags.push(tag);
   }
@@ -280,7 +280,7 @@ export default class GraphiteQuery {
       return;
     }
 
-    let newTagParam = renderTagString(tag);
+    const newTagParam = renderTagString(tag);
     this.getSeriesByTagFunc().params[tagIndex] = newTagParam;
     this.tags[tagIndex] = tag;
   }
diff --git a/public/app/plugins/datasource/graphite/query_ctrl.ts b/public/app/plugins/datasource/graphite/query_ctrl.ts
index 0563de61705..f73c21e4cc7 100644
--- a/public/app/plugins/datasource/graphite/query_ctrl.ts
+++ b/public/app/plugins/datasource/graphite/query_ctrl.ts
@@ -49,7 +49,7 @@ export class GraphiteQueryCtrl extends QueryCtrl {
       return this.uiSegmentSrv.newSegment(segment);
     });
 
-    let checkOtherSegmentsIndex = this.queryModel.checkOtherSegmentsIndex || 0;
+    const checkOtherSegmentsIndex = this.queryModel.checkOtherSegmentsIndex || 0;
     this.checkOtherSegments(checkOtherSegmentsIndex);
 
     if (this.queryModel.seriesByTagUsed) {
@@ -195,7 +195,7 @@ export class GraphiteQueryCtrl extends QueryCtrl {
     }
 
     if (segment.type === 'tag') {
-      let tag = removeTagPrefix(segment.value);
+      const tag = removeTagPrefix(segment.value);
       this.pause();
       this.addSeriesByTagFunc(tag);
       return;
@@ -273,10 +273,10 @@ export class GraphiteQueryCtrl extends QueryCtrl {
   }
 
   addSeriesByTagFunc(tag) {
-    let newFunc = this.datasource.createFuncInstance('seriesByTag', {
+    const newFunc = this.datasource.createFuncInstance('seriesByTag', {
       withDefaultParams: false,
     });
-    let tagParam = `${tag}=`;
+    const tagParam = `${tag}=`;
     newFunc.params = [tagParam];
     this.queryModel.addFunction(newFunc);
     newFunc.added = true;
@@ -303,23 +303,23 @@ export class GraphiteQueryCtrl extends QueryCtrl {
 
   getAllTags() {
     return this.datasource.getTags().then(values => {
-      let altTags = _.map(values, 'text');
+      const altTags = _.map(values, 'text');
       altTags.splice(0, 0, this.removeTagValue);
       return mapToDropdownOptions(altTags);
     });
   }
 
   getTags(index, tagPrefix) {
-    let tagExpressions = this.queryModel.renderTagExpressions(index);
+    const tagExpressions = this.queryModel.renderTagExpressions(index);
     return this.datasource.getTagsAutoComplete(tagExpressions, tagPrefix).then(values => {
-      let altTags = _.map(values, 'text');
+      const altTags = _.map(values, 'text');
       altTags.splice(0, 0, this.removeTagValue);
       return mapToDropdownOptions(altTags);
     });
   }
 
   getTagsAsSegments(tagPrefix) {
-    let tagExpressions = this.queryModel.renderTagExpressions();
+    const tagExpressions = this.queryModel.renderTagExpressions();
     return this.datasource.getTagsAutoComplete(tagExpressions, tagPrefix).then(values => {
       return _.map(values, val => {
         return this.uiSegmentSrv.newSegment({
@@ -336,18 +336,18 @@ export class GraphiteQueryCtrl extends QueryCtrl {
   }
 
   getAllTagValues(tag) {
-    let tagKey = tag.key;
+    const tagKey = tag.key;
     return this.datasource.getTagValues(tagKey).then(values => {
-      let altValues = _.map(values, 'text');
+      const altValues = _.map(values, 'text');
       return mapToDropdownOptions(altValues);
     });
   }
 
   getTagValues(tag, index, valuePrefix) {
-    let tagExpressions = this.queryModel.renderTagExpressions(index);
-    let tagKey = tag.key;
+    const tagExpressions = this.queryModel.renderTagExpressions(index);
+    const tagKey = tag.key;
     return this.datasource.getTagValuesAutoComplete(tagExpressions, tagKey, valuePrefix).then(values => {
-      let altValues = _.map(values, 'text');
+      const altValues = _.map(values, 'text');
       // Add template variables as additional values
       _.eachRight(this.templateSrv.variables, variable => {
         altValues.push('${' + variable.name + ':regex}');
@@ -362,8 +362,8 @@ export class GraphiteQueryCtrl extends QueryCtrl {
   }
 
   addNewTag(segment) {
-    let newTagKey = segment.value;
-    let newTag = { key: newTagKey, operator: '=', value: '' };
+    const newTagKey = segment.value;
+    const newTag = { key: newTagKey, operator: '=', value: '' };
     this.queryModel.addTag(newTag);
     this.targetChanged();
     this.fixTagSegments();
diff --git a/public/app/plugins/datasource/graphite/specs/datasource.test.ts b/public/app/plugins/datasource/graphite/specs/datasource.test.ts
index f94378c57a6..826f2fed344 100644
--- a/public/app/plugins/datasource/graphite/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/graphite/specs/datasource.test.ts
@@ -5,7 +5,7 @@ import $q from 'q';
 import { TemplateSrvStub } from 'test/specs/helpers';
 
 describe('graphiteDatasource', () => {
-  let ctx: any = {
+  const ctx: any = {
     backendSrv: {},
     $q: $q,
     templateSrv: new TemplateSrvStub(),
@@ -18,7 +18,7 @@ describe('graphiteDatasource', () => {
   });
 
   describe('When querying graphite with one target using query editor target spec', function() {
-    let query = {
+    const query = {
       panelId: 3,
       dashboardId: 5,
       rangeRaw: { from: 'now-1h', to: 'now' },
@@ -56,7 +56,7 @@ describe('graphiteDatasource', () => {
     });
 
     it('should query correctly', function() {
-      let params = requestOptions.data.split('&');
+      const params = requestOptions.data.split('&');
       expect(params).toContain('target=prod1.count');
       expect(params).toContain('target=prod2.count');
       expect(params).toContain('from=-1h');
@@ -64,7 +64,7 @@ describe('graphiteDatasource', () => {
     });
 
     it('should exclude undefined params', function() {
-      let params = requestOptions.data.split('&');
+      const params = requestOptions.data.split('&');
       expect(params).not.toContain('cacheTimeout=undefined');
     });
 
@@ -157,28 +157,28 @@ describe('graphiteDatasource', () => {
 
   describe('building graphite params', function() {
     it('should return empty array if no targets', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{}],
       });
       expect(results.length).toBe(0);
     });
 
     it('should uri escape targets', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{ target: 'prod1.{test,test2}' }, { target: 'prod2.count' }],
       });
       expect(results).toContain('target=prod1.%7Btest%2Ctest2%7D');
     });
 
     it('should replace target placeholder', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{ target: 'series1' }, { target: 'series2' }, { target: 'asPercent(#A,#B)' }],
       });
       expect(results[2]).toBe('target=asPercent(series1%2Cseries2)');
     });
 
     it('should replace target placeholder for hidden series', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [
           { target: 'series1', hide: true },
           { target: 'sumSeries(#A)', hide: true },
@@ -189,28 +189,28 @@ describe('graphiteDatasource', () => {
     });
 
     it('should replace target placeholder when nesting query references', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{ target: 'series1' }, { target: 'sumSeries(#A)' }, { target: 'asPercent(#A,#B)' }],
       });
       expect(results[2]).toBe('target=' + encodeURIComponent('asPercent(series1,sumSeries(series1))'));
     });
 
     it('should fix wrong minute interval parameters', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{ target: "summarize(prod.25m.count, '25m', 'sum')" }],
       });
       expect(results[0]).toBe('target=' + encodeURIComponent("summarize(prod.25m.count, '25min', 'sum')"));
     });
 
     it('should fix wrong month interval parameters', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{ target: "summarize(prod.5M.count, '5M', 'sum')" }],
       });
       expect(results[0]).toBe('target=' + encodeURIComponent("summarize(prod.5M.count, '5mon', 'sum')"));
     });
 
     it('should ignore empty targets', function() {
-      let results = ctx.ds.buildGraphiteParams({
+      const results = ctx.ds.buildGraphiteParams({
         targets: [{ target: 'series1' }, { target: '' }],
       });
       expect(results.length).toBe(2);
@@ -308,19 +308,19 @@ describe('graphiteDatasource', () => {
 
 function accessScenario(name, url, fn) {
   describe('access scenario ' + name, function() {
-    let ctx: any = {
+    const ctx: any = {
       backendSrv: {},
       $q: $q,
       templateSrv: new TemplateSrvStub(),
       instanceSettings: { url: 'url', name: 'graphiteProd', jsonData: {} },
     };
 
-    let httpOptions = {
+    const httpOptions = {
       headers: {},
     };
 
     describe('when using proxy mode', () => {
-      let options = { dashboardId: 1, panelId: 2 };
+      const options = { dashboardId: 1, panelId: 2 };
 
       it('tracing headers should be added', () => {
         ctx.instanceSettings.url = url;
diff --git a/public/app/plugins/datasource/graphite/specs/graphite_query.test.ts b/public/app/plugins/datasource/graphite/specs/graphite_query.test.ts
index d54caae05f8..2169db16c25 100644
--- a/public/app/plugins/datasource/graphite/specs/graphite_query.test.ts
+++ b/public/app/plugins/datasource/graphite/specs/graphite_query.test.ts
@@ -2,7 +2,7 @@ import gfunc from '../gfunc';
 import GraphiteQuery from '../graphite_query';
 
 describe('Graphite query model', () => {
-  let ctx: any = {
+  const ctx: any = {
     datasource: {
       getFuncDef: gfunc.getFuncDef,
       getFuncDefs: jest.fn().mockReturnValue(Promise.resolve(gfunc.getFuncDefs('1.0'))),
diff --git a/public/app/plugins/datasource/graphite/specs/query_ctrl.test.ts b/public/app/plugins/datasource/graphite/specs/query_ctrl.test.ts
index b38ad56427b..7826a458968 100644
--- a/public/app/plugins/datasource/graphite/specs/query_ctrl.test.ts
+++ b/public/app/plugins/datasource/graphite/specs/query_ctrl.test.ts
@@ -3,7 +3,7 @@ import gfunc from '../gfunc';
 import { GraphiteQueryCtrl } from '../query_ctrl';
 
 describe('GraphiteQueryCtrl', () => {
-  let ctx = <any>{
+  const ctx = <any>{
     datasource: {
       metricFindQuery: jest.fn(() => Promise.resolve([])),
       getFuncDefs: jest.fn(() => Promise.resolve(gfunc.getFuncDefs('1.0'))),
diff --git a/public/app/plugins/datasource/influxdb/datasource.ts b/public/app/plugins/datasource/influxdb/datasource.ts
index b9f2b2e03fb..8f5850fa0e8 100644
--- a/public/app/plugins/datasource/influxdb/datasource.ts
+++ b/public/app/plugins/datasource/influxdb/datasource.ts
@@ -147,15 +147,15 @@ export default class InfluxDatasource {
   }
 
   targetContainsTemplate(target) {
-    for (let group of target.groupBy) {
-      for (let param of group.params) {
+    for (const group of target.groupBy) {
+      for (const param of group.params) {
         if (this.templateSrv.variableExists(param)) {
           return true;
         }
       }
     }
 
-    for (let i in target.tags) {
+    for (const i in target.tags) {
       if (this.templateSrv.variableExists(target.tags[i].value)) {
         return true;
       }
@@ -219,7 +219,7 @@ export default class InfluxDatasource {
 
     return this._seriesQuery(query)
       .then(res => {
-        let error = _.get(res, 'results[0].error');
+        const error = _.get(res, 'results[0].error');
         if (error) {
           return { status: 'error', message: error };
         }
@@ -234,7 +234,7 @@ export default class InfluxDatasource {
     const currentUrl = this.urls.shift();
     this.urls.push(currentUrl);
 
-    let params: any = {};
+    const params: any = {};
 
     if (this.username) {
       params.u = this.username;
@@ -252,7 +252,7 @@ export default class InfluxDatasource {
       data = null;
     }
 
-    let req: any = {
+    const req: any = {
       method: method,
       url: currentUrl + url,
       params: params,
diff --git a/public/app/plugins/datasource/influxdb/influx_query.ts b/public/app/plugins/datasource/influxdb/influx_query.ts
index 2ef74170068..1ad684699bf 100644
--- a/public/app/plugins/datasource/influxdb/influx_query.ts
+++ b/public/app/plugins/datasource/influxdb/influx_query.ts
@@ -202,10 +202,10 @@ export default class InfluxQuery {
     var query = 'SELECT ';
     var i, y;
     for (i = 0; i < this.selectModels.length; i++) {
-      let parts = this.selectModels[i];
+      const parts = this.selectModels[i];
       var selectText = '';
       for (y = 0; y < parts.length; y++) {
-        let part = parts[y];
+        const part = parts[y];
         selectText = part.render(selectText);
       }
 
diff --git a/public/app/plugins/datasource/influxdb/query_ctrl.ts b/public/app/plugins/datasource/influxdb/query_ctrl.ts
index 2be1ecc7bff..1b9cd2962fc 100644
--- a/public/app/plugins/datasource/influxdb/query_ctrl.ts
+++ b/public/app/plugins/datasource/influxdb/query_ctrl.ts
@@ -36,7 +36,7 @@ export class InfluxQueryCtrl extends QueryCtrl {
     }
 
     this.tagSegments = [];
-    for (let tag of this.target.tags) {
+    for (const tag of this.target.tags) {
       if (!tag.operator) {
         if (/^\/.*\/$/.test(tag.value)) {
           tag.operator = '=~';
@@ -106,7 +106,7 @@ export class InfluxQueryCtrl extends QueryCtrl {
         if (!this.queryModel.hasGroupByTime()) {
           options.push(this.uiSegmentSrv.newSegment({ value: 'time($interval)' }));
         }
-        for (let tag of tags) {
+        for (const tag of tags) {
           options.push(this.uiSegmentSrv.newSegment({ value: 'tag(' + tag.text + ')' }));
         }
         return options;
@@ -251,7 +251,7 @@ export class InfluxQueryCtrl extends QueryCtrl {
       });
 
       if (addTemplateVars) {
-        for (let variable of this.templateSrv.variables) {
+        for (const variable of this.templateSrv.variables) {
           segments.unshift(
             this.uiSegmentSrv.newSegment({
               type: 'value',
diff --git a/public/app/plugins/datasource/influxdb/specs/datasource.test.ts b/public/app/plugins/datasource/influxdb/specs/datasource.test.ts
index 10974cdad97..60f49bd4905 100644
--- a/public/app/plugins/datasource/influxdb/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/influxdb/specs/datasource.test.ts
@@ -3,7 +3,7 @@ import $q from 'q';
 import { TemplateSrvStub } from 'test/specs/helpers';
 
 describe('InfluxDataSource', () => {
-  let ctx: any = {
+  const ctx: any = {
     backendSrv: {},
     $q: $q,
     templateSrv: new TemplateSrvStub(),
@@ -16,8 +16,8 @@ describe('InfluxDataSource', () => {
   });
 
   describe('When issuing metricFindQuery', () => {
-    let query = 'SELECT max(value) FROM measurement WHERE $timeFilter';
-    let queryOptions: any = {
+    const query = 'SELECT max(value) FROM measurement WHERE $timeFilter';
+    const queryOptions: any = {
       range: {
         from: '2018-01-01T00:00:00Z',
         to: '2018-01-02T00:00:00Z',
diff --git a/public/app/plugins/datasource/influxdb/specs/query_ctrl.test.ts b/public/app/plugins/datasource/influxdb/specs/query_ctrl.test.ts
index 4e3fc47a5fd..88d4fb143cd 100644
--- a/public/app/plugins/datasource/influxdb/specs/query_ctrl.test.ts
+++ b/public/app/plugins/datasource/influxdb/specs/query_ctrl.test.ts
@@ -3,7 +3,7 @@ import { uiSegmentSrv } from 'app/core/services/segment_srv';
 import { InfluxQueryCtrl } from '../query_ctrl';
 
 describe('InfluxDBQueryCtrl', () => {
-  let ctx = <any>{};
+  const ctx = <any>{};
 
   beforeEach(() => {
     InfluxQueryCtrl.prototype.datasource = {
diff --git a/public/app/plugins/datasource/mssql/query_ctrl.ts b/public/app/plugins/datasource/mssql/query_ctrl.ts
index 884eb634f54..1b64a571c6c 100644
--- a/public/app/plugins/datasource/mssql/query_ctrl.ts
+++ b/public/app/plugins/datasource/mssql/query_ctrl.ts
@@ -59,7 +59,7 @@ export class MssqlQueryCtrl extends QueryCtrl {
     this.lastQueryMeta = null;
     this.lastQueryError = null;
 
-    let anySeriesFromQuery = _.find(dataList, { refId: this.target.refId });
+    const anySeriesFromQuery = _.find(dataList, { refId: this.target.refId });
     if (anySeriesFromQuery) {
       this.lastQueryMeta = anySeriesFromQuery.meta;
     }
@@ -67,7 +67,7 @@ export class MssqlQueryCtrl extends QueryCtrl {
 
   onDataError(err) {
     if (err.data && err.data.results) {
-      let queryRes = err.data.results[this.target.refId];
+      const queryRes = err.data.results[this.target.refId];
       if (queryRes) {
         this.lastQueryMeta = queryRes.meta;
         this.lastQueryError = queryRes.error;
diff --git a/public/app/plugins/datasource/mssql/response_parser.ts b/public/app/plugins/datasource/mssql/response_parser.ts
index b6f538707b0..0044a49fd7d 100644
--- a/public/app/plugins/datasource/mssql/response_parser.ts
+++ b/public/app/plugins/datasource/mssql/response_parser.ts
@@ -10,11 +10,11 @@ export default class ResponseParser {
       return { data: data };
     }
 
-    for (let key in res.data.results) {
-      let queryRes = res.data.results[key];
+    for (const key in res.data.results) {
+      const queryRes = res.data.results[key];
 
       if (queryRes.series) {
-        for (let series of queryRes.series) {
+        for (const series of queryRes.series) {
           data.push({
             target: series.name,
             datapoints: series.points,
@@ -25,7 +25,7 @@ export default class ResponseParser {
       }
 
       if (queryRes.tables) {
-        for (let table of queryRes.tables) {
+        for (const table of queryRes.tables) {
           table.type = 'table';
           table.refId = queryRes.refId;
           table.meta = queryRes.meta;
diff --git a/public/app/plugins/datasource/mysql/query_ctrl.ts b/public/app/plugins/datasource/mysql/query_ctrl.ts
index 4961ce9e653..1de1fb768ad 100644
--- a/public/app/plugins/datasource/mysql/query_ctrl.ts
+++ b/public/app/plugins/datasource/mysql/query_ctrl.ts
@@ -57,7 +57,7 @@ export class MysqlQueryCtrl extends QueryCtrl {
     this.lastQueryMeta = null;
     this.lastQueryError = null;
 
-    let anySeriesFromQuery = _.find(dataList, { refId: this.target.refId });
+    const anySeriesFromQuery = _.find(dataList, { refId: this.target.refId });
     if (anySeriesFromQuery) {
       this.lastQueryMeta = anySeriesFromQuery.meta;
     }
@@ -65,7 +65,7 @@ export class MysqlQueryCtrl extends QueryCtrl {
 
   onDataError(err) {
     if (err.data && err.data.results) {
-      let queryRes = err.data.results[this.target.refId];
+      const queryRes = err.data.results[this.target.refId];
       if (queryRes) {
         this.lastQueryMeta = queryRes.meta;
         this.lastQueryError = queryRes.error;
diff --git a/public/app/plugins/datasource/mysql/response_parser.ts b/public/app/plugins/datasource/mysql/response_parser.ts
index e5d8ab79f2a..339dc592ad2 100644
--- a/public/app/plugins/datasource/mysql/response_parser.ts
+++ b/public/app/plugins/datasource/mysql/response_parser.ts
@@ -10,11 +10,11 @@ export default class ResponseParser {
       return { data: data };
     }
 
-    for (let key in res.data.results) {
-      let queryRes = res.data.results[key];
+    for (const key in res.data.results) {
+      const queryRes = res.data.results[key];
 
       if (queryRes.series) {
-        for (let series of queryRes.series) {
+        for (const series of queryRes.series) {
           data.push({
             target: series.name,
             datapoints: series.points,
@@ -25,7 +25,7 @@ export default class ResponseParser {
       }
 
       if (queryRes.tables) {
-        for (let table of queryRes.tables) {
+        for (const table of queryRes.tables) {
           table.type = 'table';
           table.refId = queryRes.refId;
           table.meta = queryRes.meta;
diff --git a/public/app/plugins/datasource/mysql/specs/datasource.test.ts b/public/app/plugins/datasource/mysql/specs/datasource.test.ts
index 85fa2b8cc4e..e75ba5e32ee 100644
--- a/public/app/plugins/datasource/mysql/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/mysql/specs/datasource.test.ts
@@ -3,13 +3,13 @@ import { MysqlDatasource } from '../datasource';
 import { CustomVariable } from 'app/features/templating/custom_variable';
 
 describe('MySQLDatasource', function() {
-  let instanceSettings = { name: 'mysql' };
-  let backendSrv = {};
-  let templateSrv = {
+  const instanceSettings = { name: 'mysql' };
+  const backendSrv = {};
+  const templateSrv = {
     replace: jest.fn(text => text),
   };
 
-  let ctx = <any>{
+  const ctx = <any>{
     backendSrv,
   };
 
diff --git a/public/app/plugins/datasource/opentsdb/specs/datasource.test.ts b/public/app/plugins/datasource/opentsdb/specs/datasource.test.ts
index 73eca7cffde..befa39fc80e 100644
--- a/public/app/plugins/datasource/opentsdb/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/opentsdb/specs/datasource.test.ts
@@ -2,14 +2,14 @@ import OpenTsDatasource from '../datasource';
 import $q from 'q';
 
 describe('opentsdb', () => {
-  let ctx = <any>{
+  const ctx = <any>{
     backendSrv: {},
     ds: {},
     templateSrv: {
       replace: str => str,
     },
   };
-  let instanceSettings = { url: '', jsonData: { tsdbVersion: 1 } };
+  const instanceSettings = { url: '', jsonData: { tsdbVersion: 1 } };
 
   beforeEach(() => {
     ctx.ctrl = new OpenTsDatasource(instanceSettings, $q, ctx.backendSrv, ctx.templateSrv);
diff --git a/public/app/plugins/datasource/postgres/query_ctrl.ts b/public/app/plugins/datasource/postgres/query_ctrl.ts
index 7afd0cf7253..a9073de22cf 100644
--- a/public/app/plugins/datasource/postgres/query_ctrl.ts
+++ b/public/app/plugins/datasource/postgres/query_ctrl.ts
@@ -57,7 +57,7 @@ export class PostgresQueryCtrl extends QueryCtrl {
     this.lastQueryMeta = null;
     this.lastQueryError = null;
 
-    let anySeriesFromQuery = _.find(dataList, { refId: this.target.refId });
+    const anySeriesFromQuery = _.find(dataList, { refId: this.target.refId });
     if (anySeriesFromQuery) {
       this.lastQueryMeta = anySeriesFromQuery.meta;
     }
@@ -65,7 +65,7 @@ export class PostgresQueryCtrl extends QueryCtrl {
 
   onDataError(err) {
     if (err.data && err.data.results) {
-      let queryRes = err.data.results[this.target.refId];
+      const queryRes = err.data.results[this.target.refId];
       if (queryRes) {
         this.lastQueryMeta = queryRes.meta;
         this.lastQueryError = queryRes.error;
diff --git a/public/app/plugins/datasource/postgres/response_parser.ts b/public/app/plugins/datasource/postgres/response_parser.ts
index ebc9598468b..e7f59e13464 100644
--- a/public/app/plugins/datasource/postgres/response_parser.ts
+++ b/public/app/plugins/datasource/postgres/response_parser.ts
@@ -10,11 +10,11 @@ export default class ResponseParser {
       return { data: data };
     }
 
-    for (let key in res.data.results) {
-      let queryRes = res.data.results[key];
+    for (const key in res.data.results) {
+      const queryRes = res.data.results[key];
 
       if (queryRes.series) {
-        for (let series of queryRes.series) {
+        for (const series of queryRes.series) {
           data.push({
             target: series.name,
             datapoints: series.points,
@@ -25,7 +25,7 @@ export default class ResponseParser {
       }
 
       if (queryRes.tables) {
-        for (let table of queryRes.tables) {
+        for (const table of queryRes.tables) {
           table.type = 'table';
           table.refId = queryRes.refId;
           table.meta = queryRes.meta;
@@ -109,7 +109,7 @@ export default class ResponseParser {
     const table = data.data.results[options.annotation.name].tables[0];
 
     let timeColumnIndex = -1;
-    let titleColumnIndex = -1;
+    const titleColumnIndex = -1;
     let textColumnIndex = -1;
     let tagsColumnIndex = -1;
 
diff --git a/public/app/plugins/datasource/postgres/specs/datasource.test.ts b/public/app/plugins/datasource/postgres/specs/datasource.test.ts
index cd6f57ee3fc..ea150750687 100644
--- a/public/app/plugins/datasource/postgres/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/postgres/specs/datasource.test.ts
@@ -3,13 +3,13 @@ import { PostgresDatasource } from '../datasource';
 import { CustomVariable } from 'app/features/templating/custom_variable';
 
 describe('PostgreSQLDatasource', function() {
-  let instanceSettings = { name: 'postgresql' };
+  const instanceSettings = { name: 'postgresql' };
 
-  let backendSrv = {};
-  let templateSrv = {
+  const backendSrv = {};
+  const templateSrv = {
     replace: jest.fn(text => text),
   };
-  let ctx = <any>{
+  const ctx = <any>{
     backendSrv,
   };
 
diff --git a/public/app/plugins/datasource/prometheus/completer.ts b/public/app/plugins/datasource/prometheus/completer.ts
index 0a974378cde..396a5fc1cd7 100644
--- a/public/app/plugins/datasource/prometheus/completer.ts
+++ b/public/app/plugins/datasource/prometheus/completer.ts
@@ -24,12 +24,12 @@ export class PromCompleter {
   }
 
   getCompletions(editor, session, pos, prefix, callback) {
-    let wrappedCallback = (err, completions) => {
+    const wrappedCallback = (err, completions) => {
       completions = completions.concat(this.templateVariableCompletions);
       return callback(err, completions);
     };
 
-    let token = session.getTokenAt(pos.row, pos.column);
+    const token = session.getTokenAt(pos.row, pos.column);
 
     switch (token.type) {
       case 'entity.name.tag.label-matcher':
@@ -51,8 +51,8 @@ export class PromCompleter {
 
     if (token.type === 'paren.lparen' && token.value === '[') {
       var vectors = [];
-      for (let unit of ['s', 'm', 'h']) {
-        for (let value of [1, 5, 10, 30]) {
+      for (const unit of ['s', 'm', 'h']) {
+        for (const value of [1, 5, 10, 30]) {
           vectors.push({
             caption: value + unit,
             value: '[' + value + unit,
@@ -99,7 +99,7 @@ export class PromCompleter {
   }
 
   getCompletionsForLabelMatcherName(session, pos) {
-    let metricName = this.findMetricName(session, pos.row, pos.column);
+    const metricName = this.findMetricName(session, pos.row, pos.column);
     if (!metricName) {
       return Promise.resolve(this.transformToCompletions(['__name__', 'instance', 'job'], 'label name'));
     }
@@ -125,7 +125,7 @@ export class PromCompleter {
   }
 
   getCompletionsForLabelMatcherValue(session, pos) {
-    let metricName = this.findMetricName(session, pos.row, pos.column);
+    const metricName = this.findMetricName(session, pos.row, pos.column);
     if (!metricName) {
       return Promise.resolve([]);
     }
@@ -163,7 +163,7 @@ export class PromCompleter {
   }
 
   getCompletionsForBinaryOperator(session, pos) {
-    let keywordOperatorToken = this.findToken(session, pos.row, pos.column, 'keyword.control', null, 'identifier');
+    const keywordOperatorToken = this.findToken(session, pos.row, pos.column, 'keyword.control', null, 'identifier');
     if (!keywordOperatorToken) {
       return Promise.resolve([]);
     }
@@ -204,7 +204,7 @@ export class PromCompleter {
       case 'ignoring':
       case 'group_left':
       case 'group_right':
-        let binaryOperatorToken = this.findToken(
+        const binaryOperatorToken = this.findToken(
           session,
           keywordOperatorToken.row,
           keywordOperatorToken.column,
@@ -243,7 +243,7 @@ export class PromCompleter {
             return labelNames;
           });
         } else {
-          let metricName = this.findMetricName(session, binaryOperatorToken.row, binaryOperatorToken.column);
+          const metricName = this.findMetricName(session, binaryOperatorToken.row, binaryOperatorToken.column);
           return this.getLabelNameAndValueForExpression(metricName, 'metricName').then(result => {
             var labelNames = this.transformToCompletions(
               _.uniq(
@@ -332,7 +332,7 @@ export class PromCompleter {
         // current row
         c = 0;
         for (idx = 0; idx < tokens.length; idx++) {
-          let nc = c + tokens[idx].value.length;
+          const nc = c + tokens[idx].value.length;
           if (nc >= column) {
             break;
           }
diff --git a/public/app/plugins/datasource/prometheus/datasource.ts b/public/app/plugins/datasource/prometheus/datasource.ts
index ec214be8554..057bb55b3c3 100644
--- a/public/app/plugins/datasource/prometheus/datasource.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.ts
@@ -317,7 +317,7 @@ export class PrometheusDatasource {
 
     options = _.clone(options);
 
-    for (let target of options.targets) {
+    for (const target of options.targets) {
       if (!target.expr || target.hide) {
         continue;
       }
@@ -482,21 +482,21 @@ export class PrometheusDatasource {
       return this.$q.when([]);
     }
 
-    let scopedVars = {
+    const scopedVars = {
       __interval: { text: this.interval, value: this.interval },
       __interval_ms: { text: kbn.interval_to_ms(this.interval), value: kbn.interval_to_ms(this.interval) },
       ...this.getRangeScopedVars(),
     };
-    let interpolated = this.templateSrv.replace(query, scopedVars, this.interpolateQueryExpr);
+    const interpolated = this.templateSrv.replace(query, scopedVars, this.interpolateQueryExpr);
     var metricFindQuery = new PrometheusMetricFindQuery(this, interpolated, this.timeSrv);
     return metricFindQuery.process();
   }
 
   getRangeScopedVars() {
-    let range = this.timeSrv.timeRange();
-    let msRange = range.to.diff(range.from);
-    let sRange = Math.round(msRange / 1000);
-    let regularRange = kbn.secondsToHms(msRange / 1000);
+    const range = this.timeSrv.timeRange();
+    const msRange = range.to.diff(range.from);
+    const sRange = Math.round(msRange / 1000);
+    const regularRange = kbn.secondsToHms(msRange / 1000);
     return {
       __range_ms: { text: msRange, value: msRange },
       __range_s: { text: sRange, value: sRange },
@@ -537,7 +537,7 @@ export class PrometheusDatasource {
           })
           .value();
 
-        for (let value of series.values) {
+        for (const value of series.values) {
           if (value[1] === '1') {
             var event = {
               annotation: annotation,
@@ -557,7 +557,7 @@ export class PrometheusDatasource {
   }
 
   testDatasource() {
-    let now = new Date().getTime();
+    const now = new Date().getTime();
     return this.performInstantQuery({ expr: '1+1' }, now / 1000).then(response => {
       if (response.data.status === 'success') {
         return { status: 'success', message: 'Data source is working' };
diff --git a/public/app/plugins/datasource/prometheus/result_transformer.ts b/public/app/plugins/datasource/prometheus/result_transformer.ts
index 7cb160e2d8c..1b1420c0b46 100644
--- a/public/app/plugins/datasource/prometheus/result_transformer.ts
+++ b/public/app/plugins/datasource/prometheus/result_transformer.ts
@@ -5,21 +5,21 @@ export class ResultTransformer {
   constructor(private templateSrv) {}
 
   transform(response: any, options: any): any[] {
-    let prometheusResult = response.data.data.result;
+    const prometheusResult = response.data.data.result;
 
     if (options.format === 'table') {
       return [this.transformMetricDataToTable(prometheusResult, options.responseListLength, options.refId)];
     } else if (options.format === 'heatmap') {
       let seriesList = [];
       prometheusResult.sort(sortSeriesByLabel);
-      for (let metricData of prometheusResult) {
+      for (const metricData of prometheusResult) {
         seriesList.push(this.transformMetricData(metricData, options, options.start, options.end));
       }
       seriesList = this.transformToHistogramOverTime(seriesList);
       return seriesList;
     } else {
-      let seriesList = [];
-      for (let metricData of prometheusResult) {
+      const seriesList = [];
+      for (const metricData of prometheusResult) {
         if (response.data.data.resultType === 'matrix') {
           seriesList.push(this.transformMetricData(metricData, options, options.start, options.end));
         } else if (response.data.data.resultType === 'vector') {
@@ -44,7 +44,7 @@ export class ResultTransformer {
       throw new Error('Prometheus heatmap error: data should be a time series');
     }
 
-    for (let value of metricData.values) {
+    for (const value of metricData.values) {
       let dp_value = parseFloat(value[1]);
       if (_.isNaN(dp_value)) {
         dp_value = null;
@@ -96,7 +96,7 @@ export class ResultTransformer {
       metricLabels[label] = labelIndex + 1;
       table.columns.push({ text: label, filterable: !label.startsWith('__') });
     });
-    let valueText = resultCount > 1 ? `Value #${refId}` : 'Value';
+    const valueText = resultCount > 1 ? `Value #${refId}` : 'Value';
     table.columns.push({ text: valueText });
 
     // Populate rows, set value to empty string when label not present.
@@ -175,8 +175,8 @@ export class ResultTransformer {
     le30    30  10  35    =>    10  0   5
     */
     for (let i = seriesList.length - 1; i > 0; i--) {
-      let topSeries = seriesList[i].datapoints;
-      let bottomSeries = seriesList[i - 1].datapoints;
+      const topSeries = seriesList[i].datapoints;
+      const bottomSeries = seriesList[i - 1].datapoints;
       if (!topSeries || !bottomSeries) {
         throw new Error('Prometheus heatmap transform error: data should be a time series');
       }
diff --git a/public/app/plugins/datasource/prometheus/specs/completer.test.ts b/public/app/plugins/datasource/prometheus/specs/completer.test.ts
index b29e4d27233..59fcc6592fb 100644
--- a/public/app/plugins/datasource/prometheus/specs/completer.test.ts
+++ b/public/app/plugins/datasource/prometheus/specs/completer.test.ts
@@ -13,10 +13,10 @@ describe('Prometheus editor completer', function() {
     };
   }
 
-  let editor = {};
+  const editor = {};
 
-  let backendSrv = <BackendSrv>{};
-  let datasourceStub = new PrometheusDatasource({}, {}, backendSrv, {}, {});
+  const backendSrv = <BackendSrv>{};
+  const datasourceStub = new PrometheusDatasource({}, {}, backendSrv, {}, {});
 
   datasourceStub.performInstantQuery = jest.fn(() =>
     Promise.resolve({
@@ -36,7 +36,7 @@ describe('Prometheus editor completer', function() {
   );
   datasourceStub.performSuggestQuery = jest.fn(() => Promise.resolve(['node_cpu']));
 
-  let templateSrv = {
+  const templateSrv = {
     variables: [
       {
         name: 'var_name',
@@ -44,7 +44,7 @@ describe('Prometheus editor completer', function() {
       },
     ],
   };
-  let completer = new PromCompleter(datasourceStub, templateSrv);
+  const completer = new PromCompleter(datasourceStub, templateSrv);
 
   describe('When inside brackets', () => {
     it('Should return range vectors', () => {
diff --git a/public/app/plugins/datasource/prometheus/specs/datasource.test.ts b/public/app/plugins/datasource/prometheus/specs/datasource.test.ts
index d52019ac4cc..fd963f7986e 100644
--- a/public/app/plugins/datasource/prometheus/specs/datasource.test.ts
+++ b/public/app/plugins/datasource/prometheus/specs/datasource.test.ts
@@ -14,8 +14,8 @@ import {
 jest.mock('../metric_find_query');
 
 describe('PrometheusDatasource', () => {
-  let ctx: any = {};
-  let instanceSettings = {
+  const ctx: any = {};
+  const instanceSettings = {
     url: 'proxied',
     directUrl: 'direct',
     user: 'test',
@@ -123,7 +123,7 @@ describe('PrometheusDatasource', () => {
 
       ctx.ds.performTimeSeriesQuery = jest.fn().mockReturnValue(responseMock);
       return ctx.ds.query(ctx.query).then(result => {
-        let results = result.data;
+        const results = result.data;
         return expect(results).toMatchObject(expected);
       });
     });
@@ -153,7 +153,7 @@ describe('PrometheusDatasource', () => {
 
       ctx.ds.performTimeSeriesQuery = jest.fn().mockReturnValue(responseMock);
       return ctx.ds.query(ctx.query).then(result => {
-        let seriesLabels = _.map(result.data, 'target');
+        const seriesLabels = _.map(result.data, 'target');
         return expect(seriesLabels).toEqual(expected);
       });
     });
@@ -326,7 +326,7 @@ describe('PrometheusDatasource', () => {
 
   describe('metricFindQuery', () => {
     beforeEach(() => {
-      let query = 'query_result(topk(5,rate(http_request_duration_microseconds_count[$__interval])))';
+      const query = 'query_result(topk(5,rate(http_request_duration_microseconds_count[$__interval])))';
       ctx.templateSrvMock.replace = jest.fn();
       ctx.timeSrvMock.timeRange = () => {
         return {
@@ -343,17 +343,17 @@ describe('PrometheusDatasource', () => {
     });
 
     it('should have the correct range and range_ms', () => {
-      let range = ctx.templateSrvMock.replace.mock.calls[0][1].__range;
-      let rangeMs = ctx.templateSrvMock.replace.mock.calls[0][1].__range_ms;
-      let rangeS = ctx.templateSrvMock.replace.mock.calls[0][1].__range_s;
+      const range = ctx.templateSrvMock.replace.mock.calls[0][1].__range;
+      const rangeMs = ctx.templateSrvMock.replace.mock.calls[0][1].__range_ms;
+      const rangeS = ctx.templateSrvMock.replace.mock.calls[0][1].__range_s;
       expect(range).toEqual({ text: '21s', value: '21s' });
       expect(rangeMs).toEqual({ text: 21031, value: 21031 });
       expect(rangeS).toEqual({ text: 21, value: 21 });
     });
 
     it('should pass the default interval value', () => {
-      let interval = ctx.templateSrvMock.replace.mock.calls[0][1].__interval;
-      let intervalMs = ctx.templateSrvMock.replace.mock.calls[0][1].__interval_ms;
+      const interval = ctx.templateSrvMock.replace.mock.calls[0][1].__interval;
+      const intervalMs = ctx.templateSrvMock.replace.mock.calls[0][1].__interval_ms;
       expect(interval).toEqual({ text: '15s', value: '15s' });
       expect(intervalMs).toEqual({ text: 15000, value: 15000 });
     });
@@ -385,23 +385,23 @@ const HOUR = 60 * MINUTE;
 
 const time = ({ hours = 0, seconds = 0, minutes = 0 }) => moment(hours * HOUR + minutes * MINUTE + seconds * SECOND);
 
-let ctx = <any>{};
-let instanceSettings = {
+const ctx = <any>{};
+const instanceSettings = {
   url: 'proxied',
   directUrl: 'direct',
   user: 'test',
   password: 'mupp',
   jsonData: { httpMethod: 'GET' },
 };
-let backendSrv = <any>{
+const backendSrv = <any>{
   datasourceRequest: jest.fn(),
 };
 
-let templateSrv = {
+const templateSrv = {
   replace: jest.fn(str => str),
 };
 
-let timeSrv = {
+const timeSrv = {
   timeRange: () => {
     return { to: { diff: () => 2000 }, from: '' };
   },
@@ -420,7 +420,7 @@ describe('PrometheusDatasource', () => {
       'proxied/api/v1/query_range?query=' + encodeURIComponent('test{job="testjob"}') + '&start=60&end=240&step=60';
 
     beforeEach(async () => {
-      let response = {
+      const response = {
         data: {
           status: 'success',
           data: {
@@ -443,7 +443,7 @@ describe('PrometheusDatasource', () => {
     });
 
     it('should generate the correct query', () => {
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -465,7 +465,7 @@ describe('PrometheusDatasource', () => {
     };
 
     beforeEach(async () => {
-      let response = {
+      const response = {
         status: 'success',
         data: {
           data: {
@@ -530,7 +530,7 @@ describe('PrometheusDatasource', () => {
     };
 
     beforeEach(async () => {
-      let response = {
+      const response = {
         status: 'success',
         data: {
           data: {
@@ -553,7 +553,7 @@ describe('PrometheusDatasource', () => {
       });
     });
     it('should generate the correct query', () => {
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -579,7 +579,7 @@ describe('PrometheusDatasource', () => {
     };
 
     beforeEach(async () => {
-      let response = {
+      const response = {
         status: 'success',
         data: {
           data: {
@@ -625,7 +625,7 @@ describe('PrometheusDatasource', () => {
     };
 
     beforeEach(async () => {
-      let response = {
+      const response = {
         status: 'success',
         data: {
           data: {
@@ -664,7 +664,7 @@ describe('PrometheusDatasource', () => {
     };
 
     it('should be min interval when greater than auto interval', async () => {
-      let query = {
+      const query = {
         // 6 minute range
         range: { from: time({ minutes: 1 }), to: time({ minutes: 7 }) },
         targets: [
@@ -675,12 +675,12 @@ describe('PrometheusDatasource', () => {
         ],
         interval: '5s',
       };
-      let urlExpected = 'proxied/api/v1/query_range?query=test&start=60&end=420&step=10';
+      const urlExpected = 'proxied/api/v1/query_range?query=test&start=60&end=420&step=10';
 
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -696,7 +696,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -717,7 +717,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -734,7 +734,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -756,7 +756,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -777,7 +777,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -799,7 +799,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -821,7 +821,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -843,7 +843,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
     });
@@ -886,7 +886,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
 
@@ -925,7 +925,7 @@ describe('PrometheusDatasource', () => {
       templateSrv.replace = jest.fn(str => str);
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
 
@@ -965,7 +965,7 @@ describe('PrometheusDatasource', () => {
       templateSrv.replace = jest.fn(str => str);
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
 
@@ -1011,7 +1011,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
 
@@ -1051,7 +1051,7 @@ describe('PrometheusDatasource', () => {
       backendSrv.datasourceRequest = jest.fn(() => Promise.resolve(response));
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
 
@@ -1096,7 +1096,7 @@ describe('PrometheusDatasource', () => {
       templateSrv.replace = jest.fn(str => str);
       ctx.ds = new PrometheusDatasource(instanceSettings, q, <any>backendSrv, templateSrv, timeSrv);
       await ctx.ds.query(query);
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('GET');
       expect(res.url).toBe(urlExpected);
 
@@ -1116,7 +1116,7 @@ describe('PrometheusDatasource', () => {
 
 describe('PrometheusDatasource for POST', () => {
   //   var ctx = new helpers.ServiceTestContext();
-  let instanceSettings = {
+  const instanceSettings = {
     url: 'proxied',
     directUrl: 'direct',
     user: 'test',
@@ -1140,7 +1140,7 @@ describe('PrometheusDatasource for POST', () => {
     };
 
     beforeEach(async () => {
-      let response = {
+      const response = {
         status: 'success',
         data: {
           data: {
@@ -1161,7 +1161,7 @@ describe('PrometheusDatasource for POST', () => {
       });
     });
     it('should generate the correct query', () => {
-      let res = backendSrv.datasourceRequest.mock.calls[0][0];
+      const res = backendSrv.datasourceRequest.mock.calls[0][0];
       expect(res.method).toBe('POST');
       expect(res.url).toBe(urlExpected);
       expect(res.data).toEqual(dataExpected);
diff --git a/public/app/plugins/datasource/prometheus/specs/metric_find_query.test.ts b/public/app/plugins/datasource/prometheus/specs/metric_find_query.test.ts
index 88f6830cd31..bfbf241ba06 100644
--- a/public/app/plugins/datasource/prometheus/specs/metric_find_query.test.ts
+++ b/public/app/plugins/datasource/prometheus/specs/metric_find_query.test.ts
@@ -4,7 +4,7 @@ import PrometheusMetricFindQuery from '../metric_find_query';
 import q from 'q';
 
 describe('PrometheusMetricFindQuery', function() {
-  let instanceSettings = {
+  const instanceSettings = {
     url: 'proxied',
     directUrl: 'direct',
     user: 'test',
@@ -15,7 +15,7 @@ describe('PrometheusMetricFindQuery', function() {
     from: moment.utc('2018-04-25 10:00'),
     to: moment.utc('2018-04-25 11:00'),
   };
-  let ctx: any = {
+  const ctx: any = {
     backendSrvMock: {
       datasourceRequest: jest.fn(() => Promise.resolve({})),
     },
diff --git a/public/app/plugins/datasource/prometheus/specs/result_transformer.test.ts b/public/app/plugins/datasource/prometheus/specs/result_transformer.test.ts
index 68224121414..ac85e1374bb 100644
--- a/public/app/plugins/datasource/prometheus/specs/result_transformer.test.ts
+++ b/public/app/plugins/datasource/prometheus/specs/result_transformer.test.ts
@@ -1,7 +1,7 @@
 import { ResultTransformer } from '../result_transformer';
 
 describe('Prometheus Result Transformer', () => {
-  let ctx: any = {};
+  const ctx: any = {};
 
   beforeEach(() => {
     ctx.templateSrv = {
@@ -111,7 +111,7 @@ describe('Prometheus Result Transformer', () => {
     };
 
     it('should convert cumulative histogram to regular', () => {
-      let options = {
+      const options = {
         format: 'heatmap',
         start: 1445000010,
         end: 1445000030,
@@ -171,7 +171,7 @@ describe('Prometheus Result Transformer', () => {
           ],
         },
       };
-      let options = {
+      const options = {
         format: 'timeseries',
         start: 0,
         end: 2,
@@ -194,7 +194,7 @@ describe('Prometheus Result Transformer', () => {
           ],
         },
       };
-      let options = {
+      const options = {
         format: 'timeseries',
         step: 1,
         start: 0,
@@ -218,7 +218,7 @@ describe('Prometheus Result Transformer', () => {
           ],
         },
       };
-      let options = {
+      const options = {
         format: 'timeseries',
         step: 2,
         start: 0,
diff --git a/public/app/plugins/datasource/testdata/datasource.ts b/public/app/plugins/datasource/testdata/datasource.ts
index 327abb1d70b..3f4035830ed 100644
--- a/public/app/plugins/datasource/testdata/datasource.ts
+++ b/public/app/plugins/datasource/testdata/datasource.ts
@@ -39,7 +39,7 @@ class TestDataDatasource {
 
         if (res.results) {
           _.forEach(res.results, queryRes => {
-            for (let series of queryRes.series) {
+            for (const series of queryRes.series) {
               data.push({
                 target: series.name,
                 datapoints: series.points,
diff --git a/public/app/plugins/panel/alertlist/module.ts b/public/app/plugins/panel/alertlist/module.ts
index 55869ce626d..b171f590e94 100644
--- a/public/app/plugins/panel/alertlist/module.ts
+++ b/public/app/plugins/panel/alertlist/module.ts
@@ -42,7 +42,7 @@ class AlertListPanel extends PanelCtrl {
     this.events.on('init-edit-mode', this.onInitEditMode.bind(this));
     this.events.on('refresh', this.onRefresh.bind(this));
 
-    for (let key in this.panel.stateFilter) {
+    for (const key in this.panel.stateFilter) {
       this.stateFilter[this.panel.stateFilter[key]] = true;
     }
   }
@@ -67,7 +67,7 @@ class AlertListPanel extends PanelCtrl {
   updateStateFilter() {
     var result = [];
 
-    for (let key in this.stateFilter) {
+    for (const key in this.stateFilter) {
       if (this.stateFilter[key]) {
         result.push(key);
       }
diff --git a/public/app/plugins/panel/graph/data_processor.ts b/public/app/plugins/panel/graph/data_processor.ts
index f8162c57a10..0e75399445d 100644
--- a/public/app/plugins/panel/graph/data_processor.ts
+++ b/public/app/plugins/panel/graph/data_processor.ts
@@ -14,7 +14,7 @@ export class DataProcessor {
     var firstItem;
     if (options.dataList && options.dataList.length > 0) {
       firstItem = options.dataList[0];
-      let autoDetectMode = this.getAutoDetectXAxisMode(firstItem);
+      const autoDetectMode = this.getAutoDetectXAxisMode(firstItem);
       if (this.panel.xaxis.mode !== autoDetectMode) {
         this.panel.xaxis.mode = autoDetectMode;
         this.setPanelDefaultsForNewXAxisMode();
@@ -127,7 +127,7 @@ export class DataProcessor {
   }
 
   customHandler(dataItem) {
-    let nameField = this.panel.xaxis.name;
+    const nameField = this.panel.xaxis.name;
     if (!nameField) {
       throw {
         message: 'No field name specified to use for x-axis, check your axes settings',
@@ -159,9 +159,9 @@ export class DataProcessor {
       return [];
     }
 
-    let fields = [];
+    const fields = [];
     var firstItem = dataList[0];
-    let fieldParts = [];
+    const fieldParts = [];
 
     function getPropertiesRecursive(obj) {
       _.forEach(obj, (value, key) => {
@@ -170,7 +170,7 @@ export class DataProcessor {
           getPropertiesRecursive(value);
         } else {
           if (!onlyNumbers || _.isNumber(value)) {
-            let field = fieldParts.concat(key).join('.');
+            const field = fieldParts.concat(key).join('.');
             fields.push(field);
           }
         }
@@ -205,7 +205,7 @@ export class DataProcessor {
   }
 
   pluckDeep(obj: any, property: string) {
-    let propertyParts = property.split('.');
+    const propertyParts = property.split('.');
     let value = obj;
     for (let i = 0; i < propertyParts.length; ++i) {
       if (value[propertyParts[i]]) {
diff --git a/public/app/plugins/panel/graph/graph.ts b/public/app/plugins/panel/graph/graph.ts
index 35886aa5bf7..bfbbc855f20 100755
--- a/public/app/plugins/panel/graph/graph.ts
+++ b/public/app/plugins/panel/graph/graph.ts
@@ -148,7 +148,7 @@ class GraphElement {
 
     if ((pos.ctrlKey || pos.metaKey) && (this.dashboard.meta.canEdit || this.dashboard.meta.canMakeEditable)) {
       // Skip if range selected (added in "plotselected" event handler)
-      let isRangeSelection = pos.x !== pos.x1;
+      const isRangeSelection = pos.x !== pos.x1;
       if (!isRangeSelection) {
         setTimeout(() => {
           this.eventManager.updateTime({ from: pos.x, to: null });
@@ -269,7 +269,7 @@ class GraphElement {
     this.panel.dashes = this.panel.lines ? this.panel.dashes : false;
 
     // Populate element
-    let options: any = this.buildFlotOptions(this.panel);
+    const options: any = this.buildFlotOptions(this.panel);
     this.prepareXAxis(options, this.panel);
     this.configureYAxisOptions(this.data, options);
     this.thresholdManager.addFlotOptions(options, this.panel);
@@ -281,7 +281,7 @@ class GraphElement {
 
   buildFlotPairs(data) {
     for (let i = 0; i < data.length; i++) {
-      let series = data[i];
+      const series = data[i];
       series.data = series.getFlotPairs(series.nullPointMode || this.panel.nullPointMode);
 
       // if hidden remove points and disable stack
@@ -299,7 +299,7 @@ class GraphElement {
         options.series.bars.align = 'center';
 
         for (let i = 0; i < this.data.length; i++) {
-          let series = this.data[i];
+          const series = this.data[i];
           series.data = [[i + 1, series.stats[panel.xaxis.values[0]]]];
         }
 
@@ -310,9 +310,9 @@ class GraphElement {
         let bucketSize: number;
 
         if (this.data.length) {
-          let histMin = _.min(_.map(this.data, s => s.stats.min));
-          let histMax = _.max(_.map(this.data, s => s.stats.max));
-          let ticks = panel.xaxis.buckets || this.panelWidth / 50;
+          const histMin = _.min(_.map(this.data, s => s.stats.min));
+          const histMax = _.max(_.map(this.data, s => s.stats.max));
+          const ticks = panel.xaxis.buckets || this.panelWidth / 50;
           bucketSize = tickStep(histMin, histMax, ticks);
           options.series.bars.barWidth = bucketSize * 0.8;
           this.data = convertToHistogramData(this.data, bucketSize, this.ctrl.hiddenSeries, histMin, histMax);
@@ -362,7 +362,7 @@ class GraphElement {
       gridColor = '#a1a1a1';
     }
     const stack = panel.stack ? true : null;
-    let options = {
+    const options = {
       hooks: {
         draw: [this.drawHook.bind(this)],
         processOffset: [this.processOffsetHook.bind(this)],
@@ -481,12 +481,12 @@ class GraphElement {
 
   addXHistogramAxis(options, bucketSize) {
     let ticks, min, max;
-    let defaultTicks = this.panelWidth / 50;
+    const defaultTicks = this.panelWidth / 50;
 
     if (this.data.length && bucketSize) {
-      let tick_values = [];
-      for (let d of this.data) {
-        for (let point of d.data) {
+      const tick_values = [];
+      for (const d of this.data) {
+        for (const point of d.data) {
           tick_values[point[0]] = true;
         }
       }
diff --git a/public/app/plugins/panel/graph/graph_tooltip.ts b/public/app/plugins/panel/graph/graph_tooltip.ts
index 7bbafc453eb..da2d25b1366 100644
--- a/public/app/plugins/panel/graph/graph_tooltip.ts
+++ b/public/app/plugins/panel/graph/graph_tooltip.ts
@@ -2,20 +2,20 @@ import $ from 'jquery';
 import { appEvents } from 'app/core/core';
 
 export default function GraphTooltip(elem, dashboard, scope, getSeriesFn) {
-  let self = this;
-  let ctrl = scope.ctrl;
-  let panel = ctrl.panel;
+  const self = this;
+  const ctrl = scope.ctrl;
+  const panel = ctrl.panel;
 
-  let $tooltip = $('<div class="graph-tooltip">');
+  const $tooltip = $('<div class="graph-tooltip">');
 
   this.destroy = function() {
     $tooltip.remove();
   };
 
   this.findHoverIndexFromDataPoints = function(posX, series, last) {
-    let ps = series.datapoints.pointsize;
-    let initial = last * ps;
-    let len = series.datapoints.points.length;
+    const ps = series.datapoints.pointsize;
+    const initial = last * ps;
+    const len = series.datapoints.points.length;
     let j;
     for (j = initial; j < len; j += ps) {
       // Special case of a non stepped line, highlight the very last point just before a null point
@@ -149,7 +149,7 @@ export default function GraphTooltip(elem, dashboard, scope, getSeriesFn) {
 
   elem.mouseleave(function() {
     if (panel.tooltip.shared) {
-      let plot = elem.data().plot;
+      const plot = elem.data().plot;
       if (plot) {
         $tooltip.detach();
         plot.unhighlight();
@@ -177,25 +177,25 @@ export default function GraphTooltip(elem, dashboard, scope, getSeriesFn) {
   };
 
   this.show = function(pos, item) {
-    let plot = elem.data().plot;
-    let plotData = plot.getData();
-    let xAxes = plot.getXAxes();
-    let xMode = xAxes[0].options.mode;
-    let seriesList = getSeriesFn();
+    const plot = elem.data().plot;
+    const plotData = plot.getData();
+    const xAxes = plot.getXAxes();
+    const xMode = xAxes[0].options.mode;
+    const seriesList = getSeriesFn();
     let allSeriesMode = panel.tooltip.shared;
     let group, value, absoluteTime, hoverInfo, i, series, seriesHtml, tooltipFormat;
 
     // if panelRelY is defined another panel wants us to show a tooltip
     // get pageX from position on x axis and pageY from relative position in original panel
     if (pos.panelRelY) {
-      let pointOffset = plot.pointOffset({ x: pos.x });
+      const pointOffset = plot.pointOffset({ x: pos.x });
       if (Number.isNaN(pointOffset.left) || pointOffset.left < 0 || pointOffset.left > elem.width()) {
         self.clear(plot);
         return;
       }
       pos.pageX = elem.offset().left + pointOffset.left;
       pos.pageY = elem.offset().top + elem.height() * pos.panelRelY;
-      let isVisible =
+      const isVisible =
         pos.pageY >= $(window).scrollTop() && pos.pageY <= $(window).innerHeight() + $(window).scrollTop();
       if (!isVisible) {
         self.clear(plot);
@@ -223,7 +223,7 @@ export default function GraphTooltip(elem, dashboard, scope, getSeriesFn) {
     if (allSeriesMode) {
       plot.unhighlight();
 
-      let seriesHoverInfo = self.getMultiSeriesPlotHoverInfo(plotData, pos);
+      const seriesHoverInfo = self.getMultiSeriesPlotHoverInfo(plotData, pos);
 
       seriesHtml = '';
 
diff --git a/public/app/plugins/panel/graph/histogram.ts b/public/app/plugins/panel/graph/histogram.ts
index ad56e477a85..f8819041cba 100644
--- a/public/app/plugins/panel/graph/histogram.ts
+++ b/public/app/plugins/panel/graph/histogram.ts
@@ -7,12 +7,12 @@ import TimeSeries from 'app/core/time_series2';
  */
 export function getSeriesValues(dataList: TimeSeries[]): number[] {
   const VALUE_INDEX = 0;
-  let values = [];
+  const values = [];
 
   // Count histogam stats
   for (let i = 0; i < dataList.length; i++) {
-    let series = dataList[i];
-    let datapoints = series.datapoints;
+    const series = dataList[i];
+    const datapoints = series.datapoints;
     for (let j = 0; j < datapoints.length; j++) {
       if (datapoints[j][VALUE_INDEX] !== null) {
         values.push(datapoints[j][VALUE_INDEX]);
@@ -30,10 +30,10 @@ export function getSeriesValues(dataList: TimeSeries[]): number[] {
  * @param bucketSize
  */
 export function convertValuesToHistogram(values: number[], bucketSize: number, min: number, max: number): any[] {
-  let histogram = {};
+  const histogram = {};
 
-  let minBound = getBucketBound(min, bucketSize);
-  let maxBound = getBucketBound(max, bucketSize);
+  const minBound = getBucketBound(min, bucketSize);
+  const maxBound = getBucketBound(max, bucketSize);
   let bound = minBound;
   let n = 0;
   while (bound <= maxBound) {
@@ -43,11 +43,11 @@ export function convertValuesToHistogram(values: number[], bucketSize: number, m
   }
 
   for (let i = 0; i < values.length; i++) {
-    let bound = getBucketBound(values[i], bucketSize);
+    const bound = getBucketBound(values[i], bucketSize);
     histogram[bound] = histogram[bound] + 1;
   }
 
-  let histogam_series = _.map(histogram, (count, bound) => {
+  const histogam_series = _.map(histogram, (count, bound) => {
     return [Number(bound), count];
   });
 
@@ -68,10 +68,10 @@ export function convertToHistogramData(
   max: number
 ): any[] {
   return data.map(series => {
-    let values = getSeriesValues([series]);
+    const values = getSeriesValues([series]);
     series.histogram = true;
     if (!hiddenSeries[series.alias]) {
-      let histogram = convertValuesToHistogram(values, bucketSize, min, max);
+      const histogram = convertValuesToHistogram(values, bucketSize, min, max);
       series.data = histogram;
     } else {
       series.data = [];
diff --git a/public/app/plugins/panel/graph/jquery.flot.events.ts b/public/app/plugins/panel/graph/jquery.flot.events.ts
index 9dfe0a8573f..2f05a76d02b 100644
--- a/public/app/plugins/panel/graph/jquery.flot.events.ts
+++ b/public/app/plugins/panel/graph/jquery.flot.events.ts
@@ -5,16 +5,16 @@ import Drop from 'tether-drop';
 
 /** @ngInject */
 export function createAnnotationToolip(element, event, plot) {
-  let injector = angular.element(document).injector();
-  let content = document.createElement('div');
+  const injector = angular.element(document).injector();
+  const content = document.createElement('div');
   content.innerHTML = '<annotation-tooltip event="event" on-edit="onEdit()"></annotation-tooltip>';
 
   injector.invoke([
     '$compile',
     '$rootScope',
     function($compile, $rootScope) {
-      let eventManager = plot.getOptions().events.manager;
-      let tmpScope = $rootScope.$new(true);
+      const eventManager = plot.getOptions().events.manager;
+      const tmpScope = $rootScope.$new(true);
       tmpScope.event = event;
       tmpScope.onEdit = function() {
         eventManager.editEvent(event);
@@ -24,7 +24,7 @@ export function createAnnotationToolip(element, event, plot) {
       tmpScope.$digest();
       tmpScope.$destroy();
 
-      let drop = new Drop({
+      const drop = new Drop({
         target: element[0],
         content: content,
         position: 'bottom center',
@@ -51,7 +51,7 @@ let markerElementToAttachTo = null;
 
 /** @ngInject */
 export function createEditPopover(element, event, plot) {
-  let eventManager = plot.getOptions().events.manager;
+  const eventManager = plot.getOptions().events.manager;
   if (eventManager.editorOpen) {
     // update marker element to attach to (needed in case of legend on the right
     // when there is a double render pass and the inital marker element is removed)
@@ -66,15 +66,15 @@ export function createEditPopover(element, event, plot) {
 
   // wait for element to be attached and positioned
   setTimeout(function() {
-    let injector = angular.element(document).injector();
-    let content = document.createElement('div');
+    const injector = angular.element(document).injector();
+    const content = document.createElement('div');
     content.innerHTML = '<event-editor panel-ctrl="panelCtrl" event="event" close="close()"></event-editor>';
 
     injector.invoke([
       '$compile',
       '$rootScope',
       function($compile, $rootScope) {
-        let scope = $rootScope.$new(true);
+        const scope = $rootScope.$new(true);
         let drop;
 
         scope.event = event;
@@ -240,22 +240,22 @@ export class EventMarkers {
    * create internal objects for the given events
    */
   setupEvents(events) {
-    let parts = _.partition(events, 'isRegion');
-    let regions = parts[0];
+    const parts = _.partition(events, 'isRegion');
+    const regions = parts[0];
     events = parts[1];
 
     $.each(events, (index, event) => {
-      let ve = new VisualEvent(event, this._buildDiv(event));
+      const ve = new VisualEvent(event, this._buildDiv(event));
       this._events.push(ve);
     });
 
     $.each(regions, (index, event) => {
-      let vre = new VisualEvent(event, this._buildRegDiv(event));
+      const vre = new VisualEvent(event, this._buildRegDiv(event));
       this._events.push(vre);
     });
 
     this._events.sort((a, b) => {
-      let ao = a.getOptions(),
+      const ao = a.getOptions(),
         bo = b.getOptions();
       if (ao.min > bo.min) {
         return 1;
@@ -293,7 +293,7 @@ export class EventMarkers {
     let o = this._plot.getPlotOffset(),
       left,
       top;
-    let xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
+    const xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
 
     $.each(this._events, (index, event) => {
       top = o.top + this._plot.height() - event.visual().height();
@@ -316,16 +316,16 @@ export class EventMarkers {
    * create a DOM element for the given event
    */
   _buildDiv(event) {
-    let that = this;
+    const that = this;
 
-    let container = this._plot.getPlaceholder();
-    let o = this._plot.getPlotOffset();
-    let xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
+    const container = this._plot.getPlaceholder();
+    const o = this._plot.getPlotOffset();
+    const xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
     let top, left, color, markerSize, markerShow, lineStyle, lineWidth;
     let markerTooltip;
 
     // map the eventType to a types object
-    let eventTypeId = event.eventType;
+    const eventTypeId = event.eventType;
 
     if (this._types === null || !this._types[eventTypeId] || !this._types[eventTypeId].color) {
       color = '#666';
@@ -369,7 +369,7 @@ export class EventMarkers {
     top = o.top + this._plot.height() + topOffset;
     left = xaxis.p2c(event.min) + o.left;
 
-    let line = $('<div class="events_line flot-temp-elem"></div>')
+    const line = $('<div class="events_line flot-temp-elem"></div>')
       .css({
         position: 'absolute',
         opacity: 0.8,
@@ -385,7 +385,7 @@ export class EventMarkers {
       .appendTo(container);
 
     if (markerShow) {
-      let marker = $('<div class="events_marker"></div>').css({
+      const marker = $('<div class="events_marker"></div>').css({
         position: 'absolute',
         left: -markerSize - Math.round(lineWidth / 2) + 'px',
         'font-size': 0,
@@ -420,7 +420,7 @@ export class EventMarkers {
         event: event,
       });
 
-      let mouseenter = function() {
+      const mouseenter = function() {
         createAnnotationToolip(marker, $(this).data('event'), that._plot);
       };
 
@@ -428,7 +428,7 @@ export class EventMarkers {
         createEditPopover(marker, event.editModel, that._plot);
       }
 
-      let mouseleave = function() {
+      const mouseleave = function() {
         that._plot.clearSelection();
       };
 
@@ -438,7 +438,7 @@ export class EventMarkers {
       }
     }
 
-    let drawableEvent = new DrawableEvent(
+    const drawableEvent = new DrawableEvent(
       line,
       function drawFunc(obj) {
         obj.show();
@@ -465,15 +465,15 @@ export class EventMarkers {
    * create a DOM element for the given region
    */
   _buildRegDiv(event) {
-    let that = this;
+    const that = this;
 
-    let container = this._plot.getPlaceholder();
-    let o = this._plot.getPlotOffset();
-    let xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
+    const container = this._plot.getPlaceholder();
+    const o = this._plot.getPlotOffset();
+    const xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
     let top, left, lineWidth, regionWidth, lineStyle, color, markerTooltip;
 
     // map the eventType to a types object
-    let eventTypeId = event.eventType;
+    const eventTypeId = event.eventType;
 
     if (this._types === null || !this._types[eventTypeId] || !this._types[eventTypeId].color) {
       color = '#666';
@@ -499,17 +499,17 @@ export class EventMarkers {
       lineStyle = this._types[eventTypeId].lineStyle.toLowerCase();
     }
 
-    let topOffset = 2;
+    const topOffset = 2;
     top = o.top + this._plot.height() + topOffset;
 
-    let timeFrom = Math.min(event.min, event.timeEnd);
-    let timeTo = Math.max(event.min, event.timeEnd);
+    const timeFrom = Math.min(event.min, event.timeEnd);
+    const timeTo = Math.max(event.min, event.timeEnd);
     left = xaxis.p2c(timeFrom) + o.left;
-    let right = xaxis.p2c(timeTo) + o.left;
+    const right = xaxis.p2c(timeTo) + o.left;
     regionWidth = right - left;
 
     _.each([left, right], position => {
-      let line = $('<div class="events_line flot-temp-elem"></div>').css({
+      const line = $('<div class="events_line flot-temp-elem"></div>').css({
         position: 'absolute',
         opacity: 0.8,
         left: position + 'px',
@@ -524,7 +524,7 @@ export class EventMarkers {
       line.appendTo(container);
     });
 
-    let region = $('<div class="events_marker region_marker flot-temp-elem"></div>').css({
+    const region = $('<div class="events_marker region_marker flot-temp-elem"></div>').css({
       position: 'absolute',
       opacity: 0.5,
       left: left + 'px',
@@ -541,7 +541,7 @@ export class EventMarkers {
       event: event,
     });
 
-    let mouseenter = function() {
+    const mouseenter = function() {
       createAnnotationToolip(region, $(this).data('event'), that._plot);
     };
 
@@ -549,7 +549,7 @@ export class EventMarkers {
       createEditPopover(region, event.editModel, that._plot);
     }
 
-    let mouseleave = function() {
+    const mouseleave = function() {
       that._plot.clearSelection();
     };
 
@@ -558,7 +558,7 @@ export class EventMarkers {
       region.hover(mouseenter, mouseleave);
     }
 
-    let drawableEvent = new DrawableEvent(
+    const drawableEvent = new DrawableEvent(
       region,
       function drawFunc(obj) {
         obj.show();
@@ -585,8 +585,8 @@ export class EventMarkers {
    * check if the event is inside visible range
    */
   _insidePlot(x) {
-    let xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
-    let xc = xaxis.p2c(x);
+    const xaxis = this._plot.getXAxes()[this._plot.getOptions().events.xaxis - 1];
+    const xc = xaxis.p2c(x);
     return xc > 0 && xc < xaxis.p2c(xaxis.max);
   }
 }
@@ -598,8 +598,8 @@ export class EventMarkers {
 /** @ngInject */
 export function init(plot) {
   /*jshint validthis:true */
-  let that = this;
-  let eventMarkers = new EventMarkers(plot);
+  const that = this;
+  const eventMarkers = new EventMarkers(plot);
 
   plot.getEvents = function() {
     return eventMarkers._events;
@@ -638,7 +638,7 @@ export function init(plot) {
   });
 
   plot.hooks.draw.push(function(plot) {
-    let options = plot.getOptions();
+    const options = plot.getOptions();
 
     if (eventMarkers.eventsEnabled) {
       // check for first run
@@ -654,7 +654,7 @@ export function init(plot) {
   });
 }
 
-let defaultOptions = {
+const defaultOptions = {
   events: {
     data: null,
     types: null,
diff --git a/public/app/plugins/panel/graph/legend.ts b/public/app/plugins/panel/graph/legend.ts
index f5c35ad98bf..f735fe28b22 100644
--- a/public/app/plugins/panel/graph/legend.ts
+++ b/public/app/plugins/panel/graph/legend.ts
@@ -16,7 +16,7 @@ module.directive('graphLegend', function(popoverSrv, $timeout) {
       var i;
       var legendScrollbar;
       const legendRightDefaultWidth = 10;
-      let legendElem = elem.parent();
+      const legendElem = elem.parent();
 
       scope.$on('$destroy', function() {
         destroyScrollbar();
@@ -111,7 +111,7 @@ module.directive('graphLegend', function(popoverSrv, $timeout) {
       }
 
       function render() {
-        let legendWidth = legendElem.width();
+        const legendWidth = legendElem.width();
         if (!ctrl.panel.legend.show) {
           elem.empty();
           firstRender = true;
@@ -176,7 +176,7 @@ module.directive('graphLegend', function(popoverSrv, $timeout) {
       }
 
       function renderSeriesLegendElements() {
-        let seriesElements = [];
+        const seriesElements = [];
         for (i = 0; i < seriesList.length; i++) {
           var series = seriesList[i];
 
@@ -231,7 +231,7 @@ module.directive('graphLegend', function(popoverSrv, $timeout) {
       }
 
       function renderLegendElement(tableHeaderElem) {
-        let legendWidth = elem.width();
+        const legendWidth = elem.width();
 
         var seriesElements = renderSeriesLegendElements();
 
@@ -262,8 +262,8 @@ module.directive('graphLegend', function(popoverSrv, $timeout) {
           </div>
         `;
 
-        let scrollRoot = elem;
-        let scroller = elem.find('.graph-legend-scroll');
+        const scrollRoot = elem;
+        const scroller = elem.find('.graph-legend-scroll');
 
         // clear existing scroll bar track to prevent duplication
         scrollRoot.find('.baron__track').remove();
@@ -272,7 +272,7 @@ module.directive('graphLegend', function(popoverSrv, $timeout) {
         $(scrollBarHTML).appendTo(scrollRoot);
         scroller.addClass(scrollerClass);
 
-        let scrollbarParams = {
+        const scrollbarParams = {
           root: scrollRoot[0],
           scroller: scroller[0],
           bar: '.baron__bar',
diff --git a/public/app/plugins/panel/graph/module.ts b/public/app/plugins/panel/graph/module.ts
index ba151692147..97999158446 100644
--- a/public/app/plugins/panel/graph/module.ts
+++ b/public/app/plugins/panel/graph/module.ts
@@ -196,7 +196,7 @@ class GraphCtrl extends MetricsPanelCtrl {
         tip: 'No datapoints returned from data query',
       };
     } else {
-      for (let series of this.seriesList) {
+      for (const series of this.seriesList) {
         if (series.isOutsideRange) {
           this.dataWarning = {
             title: 'Data points outside time range',
@@ -226,7 +226,7 @@ class GraphCtrl extends MetricsPanelCtrl {
       return;
     }
 
-    for (let series of this.seriesList) {
+    for (const series of this.seriesList) {
       series.applySeriesOverrides(this.panel.seriesOverrides);
 
       if (series.unit) {
diff --git a/public/app/plugins/panel/graph/specs/graph.test.ts b/public/app/plugins/panel/graph/specs/graph.test.ts
index f75f7cd68ea..2ae76bb9c9c 100644
--- a/public/app/plugins/panel/graph/specs/graph.test.ts
+++ b/public/app/plugins/panel/graph/specs/graph.test.ts
@@ -28,9 +28,9 @@ import moment from 'moment';
 import $ from 'jquery';
 import { graphDirective } from '../graph';
 
-let ctx = <any>{};
+const ctx = <any>{};
 let ctrl;
-let scope = {
+const scope = {
   ctrl: {},
   range: {
     from: moment([2015, 1, 1]),
diff --git a/public/app/plugins/panel/graph/specs/graph_ctrl.test.ts b/public/app/plugins/panel/graph/specs/graph_ctrl.test.ts
index a0c7dd0ab9c..49efa8d4120 100644
--- a/public/app/plugins/panel/graph/specs/graph_ctrl.test.ts
+++ b/public/app/plugins/panel/graph/specs/graph_ctrl.test.ts
@@ -4,7 +4,7 @@ import { GraphCtrl } from '../module';
 jest.mock('../graph', () => ({}));
 
 describe('GraphCtrl', () => {
-  let injector = {
+  const injector = {
     get: () => {
       return {
         timeRange: () => {
@@ -17,7 +17,7 @@ describe('GraphCtrl', () => {
     },
   };
 
-  let scope = {
+  const scope = {
     $on: () => {},
   };
 
@@ -30,7 +30,7 @@ describe('GraphCtrl', () => {
     },
   };
 
-  let ctx = <any>{};
+  const ctx = <any>{};
 
   beforeEach(() => {
     ctx.ctrl = new GraphCtrl(scope, injector, {});
diff --git a/public/app/plugins/panel/graph/specs/histogram.test.ts b/public/app/plugins/panel/graph/specs/histogram.test.ts
index 0e9eaa8b98e..adbc0fcba68 100644
--- a/public/app/plugins/panel/graph/specs/histogram.test.ts
+++ b/public/app/plugins/panel/graph/specs/histogram.test.ts
@@ -11,17 +11,17 @@ describe('Graph Histogam Converter', function() {
 
     it('Should convert to series-like array', () => {
       bucketSize = 10;
-      let expected = [[0, 2], [10, 3], [20, 2]];
+      const expected = [[0, 2], [10, 3], [20, 2]];
 
-      let histogram = convertValuesToHistogram(values, bucketSize, 1, 29);
+      const histogram = convertValuesToHistogram(values, bucketSize, 1, 29);
       expect(histogram).toMatchObject(expected);
     });
 
     it('Should not add empty buckets', () => {
       bucketSize = 5;
-      let expected = [[0, 2], [5, 0], [10, 2], [15, 1], [20, 1], [25, 1]];
+      const expected = [[0, 2], [5, 0], [10, 2], [15, 1], [20, 1], [25, 1]];
 
-      let histogram = convertValuesToHistogram(values, bucketSize, 1, 29);
+      const histogram = convertValuesToHistogram(values, bucketSize, 1, 29);
       expect(histogram).toMatchObject(expected);
     });
   });
@@ -38,18 +38,18 @@ describe('Graph Histogam Converter', function() {
     });
 
     it('Should convert to values array', () => {
-      let expected = [1, 2, 10, 11, 17, 20, 29];
+      const expected = [1, 2, 10, 11, 17, 20, 29];
 
-      let values = getSeriesValues(data);
+      const values = getSeriesValues(data);
       expect(values).toMatchObject(expected);
     });
 
     it('Should skip null values', () => {
       data[0].datapoints.push([null, 0]);
 
-      let expected = [1, 2, 10, 11, 17, 20, 29];
+      const expected = [1, 2, 10, 11, 17, 20, 29];
 
-      let values = getSeriesValues(data);
+      const values = getSeriesValues(data);
       expect(values).toMatchObject(expected);
     });
   });
diff --git a/public/app/plugins/panel/graph/specs/series_override_ctrl.test.ts b/public/app/plugins/panel/graph/specs/series_override_ctrl.test.ts
index 2e7456a132a..40b6c1ba561 100644
--- a/public/app/plugins/panel/graph/specs/series_override_ctrl.test.ts
+++ b/public/app/plugins/panel/graph/specs/series_override_ctrl.test.ts
@@ -2,7 +2,7 @@ import '../series_overrides_ctrl';
 import { SeriesOverridesCtrl } from '../series_overrides_ctrl';
 
 describe('SeriesOverridesCtrl', () => {
-  let popoverSrv = {};
+  const popoverSrv = {};
   let $scope;
 
   beforeEach(() => {
diff --git a/public/app/plugins/panel/heatmap/color_legend.ts b/public/app/plugins/panel/heatmap/color_legend.ts
index cae1e5fac7f..84ecd2389b6 100644
--- a/public/app/plugins/panel/heatmap/color_legend.ts
+++ b/public/app/plugins/panel/heatmap/color_legend.ts
@@ -6,7 +6,7 @@ import { contextSrv } from 'app/core/core';
 import { tickStep } from 'app/core/utils/ticks';
 import { getColorScale, getOpacityScale } from './color_scale';
 
-let module = angular.module('grafana.directives');
+const module = angular.module('grafana.directives');
 
 const LEGEND_HEIGHT_PX = 6;
 const LEGEND_WIDTH_PX = 100;
@@ -21,8 +21,8 @@ module.directive('colorLegend', function() {
     restrict: 'E',
     template: '<div class="heatmap-color-legend"><svg width="16.5rem" height="24px"></svg></div>',
     link: function(scope, elem, attrs) {
-      let ctrl = scope.ctrl;
-      let panel = scope.ctrl.panel;
+      const ctrl = scope.ctrl;
+      const panel = scope.ctrl.panel;
 
       render();
 
@@ -31,17 +31,17 @@ module.directive('colorLegend', function() {
       });
 
       function render() {
-        let legendElem = $(elem).find('svg');
-        let legendWidth = Math.floor(legendElem.outerWidth());
+        const legendElem = $(elem).find('svg');
+        const legendWidth = Math.floor(legendElem.outerWidth());
 
         if (panel.color.mode === 'spectrum') {
-          let colorScheme = _.find(ctrl.colorSchemes, {
+          const colorScheme = _.find(ctrl.colorSchemes, {
             value: panel.color.colorScheme,
           });
-          let colorScale = getColorScale(colorScheme, contextSrv.user.lightTheme, legendWidth);
+          const colorScale = getColorScale(colorScheme, contextSrv.user.lightTheme, legendWidth);
           drawSimpleColorLegend(elem, colorScale);
         } else if (panel.color.mode === 'opacity') {
-          let colorOptions = panel.color;
+          const colorOptions = panel.color;
           drawSimpleOpacityLegend(elem, colorOptions);
         }
       }
@@ -57,8 +57,8 @@ module.directive('heatmapLegend', function() {
     restrict: 'E',
     template: `<div class="heatmap-color-legend"><svg width="${LEGEND_WIDTH_PX}px" height="${LEGEND_HEIGHT_PX}px"></svg></div>`,
     link: function(scope, elem, attrs) {
-      let ctrl = scope.ctrl;
-      let panel = scope.ctrl.panel;
+      const ctrl = scope.ctrl;
+      const panel = scope.ctrl.panel;
 
       render();
       ctrl.events.on('render', function() {
@@ -68,18 +68,18 @@ module.directive('heatmapLegend', function() {
       function render() {
         clearLegend(elem);
         if (!_.isEmpty(ctrl.data) && !_.isEmpty(ctrl.data.cards)) {
-          let rangeFrom = 0;
-          let rangeTo = ctrl.data.cardStats.max;
-          let maxValue = panel.color.max || rangeTo;
-          let minValue = panel.color.min || 0;
+          const rangeFrom = 0;
+          const rangeTo = ctrl.data.cardStats.max;
+          const maxValue = panel.color.max || rangeTo;
+          const minValue = panel.color.min || 0;
 
           if (panel.color.mode === 'spectrum') {
-            let colorScheme = _.find(ctrl.colorSchemes, {
+            const colorScheme = _.find(ctrl.colorSchemes, {
               value: panel.color.colorScheme,
             });
             drawColorLegend(elem, colorScheme, rangeFrom, rangeTo, maxValue, minValue);
           } else if (panel.color.mode === 'opacity') {
-            let colorOptions = panel.color;
+            const colorOptions = panel.color;
             drawOpacityLegend(elem, colorOptions, rangeFrom, rangeTo, maxValue, minValue);
           }
         }
@@ -89,21 +89,21 @@ module.directive('heatmapLegend', function() {
 });
 
 function drawColorLegend(elem, colorScheme, rangeFrom, rangeTo, maxValue, minValue) {
-  let legendElem = $(elem).find('svg');
-  let legend = d3.select(legendElem.get(0));
+  const legendElem = $(elem).find('svg');
+  const legend = d3.select(legendElem.get(0));
   clearLegend(elem);
 
-  let legendWidth = Math.floor(legendElem.outerWidth()) - 30;
-  let legendHeight = legendElem.attr('height');
+  const legendWidth = Math.floor(legendElem.outerWidth()) - 30;
+  const legendHeight = legendElem.attr('height');
 
   let rangeStep = 1;
   if (rangeTo - rangeFrom > legendWidth) {
     rangeStep = Math.floor((rangeTo - rangeFrom) / legendWidth);
   }
-  let widthFactor = legendWidth / (rangeTo - rangeFrom);
-  let valuesRange = d3.range(rangeFrom, rangeTo, rangeStep);
+  const widthFactor = legendWidth / (rangeTo - rangeFrom);
+  const valuesRange = d3.range(rangeFrom, rangeTo, rangeStep);
 
-  let colorScale = getColorScale(colorScheme, contextSrv.user.lightTheme, maxValue, minValue);
+  const colorScale = getColorScale(colorScheme, contextSrv.user.lightTheme, maxValue, minValue);
   legend
     .selectAll('.heatmap-color-legend-rect')
     .data(valuesRange)
@@ -120,21 +120,21 @@ function drawColorLegend(elem, colorScheme, rangeFrom, rangeTo, maxValue, minVal
 }
 
 function drawOpacityLegend(elem, options, rangeFrom, rangeTo, maxValue, minValue) {
-  let legendElem = $(elem).find('svg');
-  let legend = d3.select(legendElem.get(0));
+  const legendElem = $(elem).find('svg');
+  const legend = d3.select(legendElem.get(0));
   clearLegend(elem);
 
-  let legendWidth = Math.floor(legendElem.outerWidth()) - 30;
-  let legendHeight = legendElem.attr('height');
+  const legendWidth = Math.floor(legendElem.outerWidth()) - 30;
+  const legendHeight = legendElem.attr('height');
 
   let rangeStep = 1;
   if (rangeTo - rangeFrom > legendWidth) {
     rangeStep = Math.floor((rangeTo - rangeFrom) / legendWidth);
   }
-  let widthFactor = legendWidth / (rangeTo - rangeFrom);
-  let valuesRange = d3.range(rangeFrom, rangeTo, rangeStep);
+  const widthFactor = legendWidth / (rangeTo - rangeFrom);
+  const valuesRange = d3.range(rangeFrom, rangeTo, rangeStep);
 
-  let opacityScale = getOpacityScale(options, maxValue, minValue);
+  const opacityScale = getOpacityScale(options, maxValue, minValue);
   legend
     .selectAll('.heatmap-opacity-legend-rect')
     .data(valuesRange)
@@ -152,27 +152,27 @@ function drawOpacityLegend(elem, options, rangeFrom, rangeTo, maxValue, minValue
 }
 
 function drawLegendValues(elem, colorScale, rangeFrom, rangeTo, maxValue, minValue, legendWidth) {
-  let legendElem = $(elem).find('svg');
-  let legend = d3.select(legendElem.get(0));
+  const legendElem = $(elem).find('svg');
+  const legend = d3.select(legendElem.get(0));
 
   if (legendWidth <= 0 || legendElem.get(0).childNodes.length === 0) {
     return;
   }
 
-  let legendValueScale = d3
+  const legendValueScale = d3
     .scaleLinear()
     .domain([0, rangeTo])
     .range([0, legendWidth]);
 
-  let ticks = buildLegendTicks(0, rangeTo, maxValue, minValue);
-  let xAxis = d3
+  const ticks = buildLegendTicks(0, rangeTo, maxValue, minValue);
+  const xAxis = d3
     .axisBottom(legendValueScale)
     .tickValues(ticks)
     .tickSize(LEGEND_TICK_SIZE);
 
-  let colorRect = legendElem.find(':first-child');
-  let posY = getSvgElemHeight(legendElem) + LEGEND_VALUE_MARGIN;
-  let posX = getSvgElemX(colorRect);
+  const colorRect = legendElem.find(':first-child');
+  const posY = getSvgElemHeight(legendElem) + LEGEND_VALUE_MARGIN;
+  const posX = getSvgElemX(colorRect);
 
   d3
     .select(legendElem.get(0))
@@ -188,18 +188,18 @@ function drawLegendValues(elem, colorScale, rangeFrom, rangeTo, maxValue, minVal
 }
 
 function drawSimpleColorLegend(elem, colorScale) {
-  let legendElem = $(elem).find('svg');
+  const legendElem = $(elem).find('svg');
   clearLegend(elem);
 
-  let legendWidth = Math.floor(legendElem.outerWidth());
-  let legendHeight = legendElem.attr('height');
+  const legendWidth = Math.floor(legendElem.outerWidth());
+  const legendHeight = legendElem.attr('height');
 
   if (legendWidth) {
-    let valuesNumber = Math.floor(legendWidth / 2);
-    let rangeStep = Math.floor(legendWidth / valuesNumber);
-    let valuesRange = d3.range(0, legendWidth, rangeStep);
+    const valuesNumber = Math.floor(legendWidth / 2);
+    const rangeStep = Math.floor(legendWidth / valuesNumber);
+    const valuesRange = d3.range(0, legendWidth, rangeStep);
 
-    let legend = d3.select(legendElem.get(0));
+    const legend = d3.select(legendElem.get(0));
     var legendRects = legend.selectAll('.heatmap-color-legend-rect').data(valuesRange);
 
     legendRects
@@ -215,12 +215,12 @@ function drawSimpleColorLegend(elem, colorScale) {
 }
 
 function drawSimpleOpacityLegend(elem, options) {
-  let legendElem = $(elem).find('svg');
+  const legendElem = $(elem).find('svg');
   clearLegend(elem);
 
-  let legend = d3.select(legendElem.get(0));
-  let legendWidth = Math.floor(legendElem.outerWidth());
-  let legendHeight = legendElem.attr('height');
+  const legend = d3.select(legendElem.get(0));
+  const legendWidth = Math.floor(legendElem.outerWidth());
+  const legendHeight = legendElem.attr('height');
 
   if (legendWidth) {
     let legendOpacityScale;
@@ -237,8 +237,8 @@ function drawSimpleOpacityLegend(elem, options) {
         .range([0, 1]);
     }
 
-    let rangeStep = 10;
-    let valuesRange = d3.range(0, legendWidth, rangeStep);
+    const rangeStep = 10;
+    const valuesRange = d3.range(0, legendWidth, rangeStep);
     var legendRects = legend.selectAll('.heatmap-opacity-legend-rect').data(valuesRange);
 
     legendRects
@@ -255,12 +255,12 @@ function drawSimpleOpacityLegend(elem, options) {
 }
 
 function clearLegend(elem) {
-  let legendElem = $(elem).find('svg');
+  const legendElem = $(elem).find('svg');
   legendElem.empty();
 }
 
 function getSvgElemX(elem) {
-  let svgElem = elem.get(0);
+  const svgElem = elem.get(0);
   if (svgElem && svgElem.x && svgElem.x.baseVal) {
     return svgElem.x.baseVal.value;
   } else {
@@ -269,7 +269,7 @@ function getSvgElemX(elem) {
 }
 
 function getSvgElemHeight(elem) {
-  let svgElem = elem.get(0);
+  const svgElem = elem.get(0);
   if (svgElem && svgElem.height && svgElem.height.baseVal) {
     return svgElem.height.baseVal.value;
   } else {
@@ -278,13 +278,13 @@ function getSvgElemHeight(elem) {
 }
 
 function buildLegendTicks(rangeFrom, rangeTo, maxValue, minValue) {
-  let range = rangeTo - rangeFrom;
-  let tickStepSize = tickStep(rangeFrom, rangeTo, 3);
-  let ticksNum = Math.round(range / tickStepSize);
+  const range = rangeTo - rangeFrom;
+  const tickStepSize = tickStep(rangeFrom, rangeTo, 3);
+  const ticksNum = Math.round(range / tickStepSize);
   let ticks = [];
 
   for (let i = 0; i < ticksNum; i++) {
-    let current = tickStepSize * i;
+    const current = tickStepSize * i;
     // Add user-defined min and max if it had been set
     if (isValueCloseTo(minValue, current, tickStepSize)) {
       ticks.push(minValue);
@@ -309,6 +309,6 @@ function buildLegendTicks(rangeFrom, rangeTo, maxValue, minValue) {
 }
 
 function isValueCloseTo(val, valueTo, step) {
-  let diff = Math.abs(val - valueTo);
+  const diff = Math.abs(val - valueTo);
   return diff < step * 0.3;
 }
diff --git a/public/app/plugins/panel/heatmap/color_scale.ts b/public/app/plugins/panel/heatmap/color_scale.ts
index 3550c981db2..2234deb8405 100644
--- a/public/app/plugins/panel/heatmap/color_scale.ts
+++ b/public/app/plugins/panel/heatmap/color_scale.ts
@@ -2,11 +2,11 @@ import * as d3 from 'd3';
 import * as d3ScaleChromatic from 'd3-scale-chromatic';
 
 export function getColorScale(colorScheme: any, lightTheme: boolean, maxValue: number, minValue = 0): (d: any) => any {
-  let colorInterpolator = d3ScaleChromatic[colorScheme.value];
-  let colorScaleInverted = colorScheme.invert === 'always' || colorScheme.invert === (lightTheme ? 'light' : 'dark');
+  const colorInterpolator = d3ScaleChromatic[colorScheme.value];
+  const colorScaleInverted = colorScheme.invert === 'always' || colorScheme.invert === (lightTheme ? 'light' : 'dark');
 
-  let start = colorScaleInverted ? maxValue : minValue;
-  let end = colorScaleInverted ? minValue : maxValue;
+  const start = colorScaleInverted ? maxValue : minValue;
+  const end = colorScaleInverted ? minValue : maxValue;
 
   return d3.scaleSequential(colorInterpolator).domain([start, end]);
 }
diff --git a/public/app/plugins/panel/heatmap/heatmap_ctrl.ts b/public/app/plugins/panel/heatmap/heatmap_ctrl.ts
index 1d35ff2ea84..66b72f8d37a 100644
--- a/public/app/plugins/panel/heatmap/heatmap_ctrl.ts
+++ b/public/app/plugins/panel/heatmap/heatmap_ctrl.ts
@@ -13,10 +13,10 @@ import {
   sortSeriesByLabel,
 } from './heatmap_data_converter';
 
-let X_BUCKET_NUMBER_DEFAULT = 30;
-let Y_BUCKET_NUMBER_DEFAULT = 10;
+const X_BUCKET_NUMBER_DEFAULT = 30;
+const Y_BUCKET_NUMBER_DEFAULT = 10;
 
-let panelDefaults = {
+const panelDefaults = {
   heatmap: {},
   cards: {
     cardPadding: null,
@@ -57,12 +57,12 @@ let panelDefaults = {
   highlightCards: true,
 };
 
-let colorModes = ['opacity', 'spectrum'];
-let opacityScales = ['linear', 'sqrt'];
+const colorModes = ['opacity', 'spectrum'];
+const opacityScales = ['linear', 'sqrt'];
 
 // Schemes from d3-scale-chromatic
 // https://github.com/d3/d3-scale-chromatic
-let colorSchemes = [
+const colorSchemes = [
   // Diverging
   { name: 'Spectral', value: 'interpolateSpectral', invert: 'always' },
   { name: 'RdYlGn', value: 'interpolateRdYlGn', invert: 'always' },
@@ -161,11 +161,11 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
     let xBucketSize, yBucketSize, bucketsData, heatmapStats;
     const logBase = this.panel.yAxis.logBase;
 
-    let xBucketNumber = this.panel.xBucketNumber || X_BUCKET_NUMBER_DEFAULT;
-    let xBucketSizeByNumber = Math.floor((this.range.to - this.range.from) / xBucketNumber);
+    const xBucketNumber = this.panel.xBucketNumber || X_BUCKET_NUMBER_DEFAULT;
+    const xBucketSizeByNumber = Math.floor((this.range.to - this.range.from) / xBucketNumber);
 
     // Parse X bucket size (number or interval)
-    let isIntervalString = kbn.interval_regex.test(this.panel.xBucketSize);
+    const isIntervalString = kbn.interval_regex.test(this.panel.xBucketSize);
     if (isIntervalString) {
       xBucketSize = kbn.interval_to_ms(this.panel.xBucketSize);
     } else if (
@@ -180,7 +180,7 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
 
     // Calculate Y bucket size
     heatmapStats = this.parseSeries(this.series);
-    let yBucketNumber = this.panel.yBucketNumber || Y_BUCKET_NUMBER_DEFAULT;
+    const yBucketNumber = this.panel.yBucketNumber || Y_BUCKET_NUMBER_DEFAULT;
     if (logBase !== 1) {
       yBucketSize = this.panel.yAxis.splitFactor;
     } else {
@@ -204,7 +204,7 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
       yBucketSize = 1;
     }
 
-    let { cards, cardStats } = convertToCards(bucketsData);
+    const { cards, cardStats } = convertToCards(bucketsData);
 
     this.data = {
       buckets: bucketsData,
@@ -241,12 +241,12 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
     }
 
     // Calculate bucket size based on heatmap data
-    let xBucketBoundSet = _.map(_.keys(bucketsData), key => Number(key));
+    const xBucketBoundSet = _.map(_.keys(bucketsData), key => Number(key));
     xBucketSize = calculateBucketSize(xBucketBoundSet);
     // Always let yBucketSize=1 in 'tsbuckets' mode
     yBucketSize = 1;
 
-    let { cards, cardStats } = convertToCards(bucketsData);
+    const { cards, cardStats } = convertToCards(bucketsData);
 
     this.data = {
       buckets: bucketsData,
@@ -284,7 +284,7 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
         tip: 'No datapoints returned from data query',
       };
     } else {
-      for (let series of this.series) {
+      for (const series of this.series) {
         if (series.isOutsideRange) {
           this.dataWarning = {
             title: 'Data points outside time range',
@@ -313,17 +313,17 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
       throw new Error('Heatmap error: data should be a time series');
     }
 
-    let series = new TimeSeries({
+    const series = new TimeSeries({
       datapoints: seriesData.datapoints,
       alias: seriesData.target,
     });
 
     series.flotpairs = series.getFlotPairs(this.panel.nullPointMode);
 
-    let datapoints = seriesData.datapoints || [];
+    const datapoints = seriesData.datapoints || [];
     if (datapoints && datapoints.length > 0) {
-      let last = datapoints[datapoints.length - 1][1];
-      let from = this.range.from;
+      const last = datapoints[datapoints.length - 1][1];
+      const from = this.range.from;
       if (last - from < -10000) {
         series.isOutsideRange = true;
       }
@@ -333,9 +333,9 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
   }
 
   parseSeries(series) {
-    let min = _.min(_.map(series, s => s.stats.min));
-    let minLog = _.min(_.map(series, s => s.stats.logmin));
-    let max = _.max(_.map(series, s => s.stats.max));
+    const min = _.min(_.map(series, s => s.stats.min));
+    const minLog = _.min(_.map(series, s => s.stats.logmin));
+    const max = _.max(_.map(series, s => s.stats.max));
 
     return {
       max: max,
@@ -345,10 +345,10 @@ export class HeatmapCtrl extends MetricsPanelCtrl {
   }
 
   parseHistogramSeries(series) {
-    let bounds = _.map(series, s => Number(s.alias));
-    let min = _.min(bounds);
-    let minLog = _.min(bounds);
-    let max = _.max(bounds);
+    const bounds = _.map(series, s => Number(s.alias));
+    const min = _.min(bounds);
+    const minLog = _.min(bounds);
+    const max = _.max(bounds);
 
     return {
       max: max,
diff --git a/public/app/plugins/panel/heatmap/heatmap_data_converter.ts b/public/app/plugins/panel/heatmap/heatmap_data_converter.ts
index 048b19de911..0b3f83bbe46 100644
--- a/public/app/plugins/panel/heatmap/heatmap_data_converter.ts
+++ b/public/app/plugins/panel/heatmap/heatmap_data_converter.ts
@@ -1,7 +1,7 @@
 import _ from 'lodash';
 
-let VALUE_INDEX = 0;
-let TIME_INDEX = 1;
+const VALUE_INDEX = 0;
+const TIME_INDEX = 1;
 
 interface XBucket {
   x: number;
@@ -18,18 +18,18 @@ interface YBucket {
  * @param seriesList List of time series
  */
 function histogramToHeatmap(seriesList) {
-  let heatmap = {};
+  const heatmap = {};
 
   for (let i = 0; i < seriesList.length; i++) {
-    let series = seriesList[i];
-    let bound = i;
+    const series = seriesList[i];
+    const bound = i;
     if (isNaN(bound)) {
       return heatmap;
     }
 
-    for (let point of series.datapoints) {
-      let count = point[VALUE_INDEX];
-      let time = point[TIME_INDEX];
+    for (const point of series.datapoints) {
+      const count = point[VALUE_INDEX];
+      const time = point[TIME_INDEX];
 
       if (!_.isNumber(count)) {
         continue;
@@ -101,10 +101,10 @@ function parseHistogramLabel(label: string): number {
 function convertToCards(buckets) {
   let min = 0,
     max = 0;
-  let cards = [];
+  const cards = [];
   _.forEach(buckets, xBucket => {
     _.forEach(xBucket.buckets, yBucket => {
-      let card = {
+      const card = {
         x: xBucket.x,
         y: yBucket.y,
         yBounds: yBucket.bounds,
@@ -123,7 +123,7 @@ function convertToCards(buckets) {
     });
   });
 
-  let cardStats = { min, max };
+  const cardStats = { min, max };
   return { cards, cardStats };
 }
 
@@ -146,19 +146,19 @@ function convertToCards(buckets) {
  */
 function mergeZeroBuckets(buckets, minValue) {
   _.forEach(buckets, xBucket => {
-    let yBuckets = xBucket.buckets;
+    const yBuckets = xBucket.buckets;
 
-    let emptyBucket = {
+    const emptyBucket = {
       bounds: { bottom: 0, top: 0 },
       values: [],
       points: [],
       count: 0,
     };
 
-    let nullBucket = yBuckets[0] || emptyBucket;
-    let minBucket = yBuckets[minValue] || emptyBucket;
+    const nullBucket = yBuckets[0] || emptyBucket;
+    const minBucket = yBuckets[minValue] || emptyBucket;
 
-    let newBucket = {
+    const newBucket = {
       y: 0,
       bounds: { bottom: minValue, top: minBucket.bounds.top || minValue },
       values: [],
@@ -211,11 +211,11 @@ function mergeZeroBuckets(buckets, minValue) {
  * }
  */
 function convertToHeatMap(seriesList, yBucketSize, xBucketSize, logBase = 1) {
-  let heatmap = {};
+  const heatmap = {};
 
-  for (let series of seriesList) {
-    let datapoints = series.datapoints;
-    let seriesName = series.label;
+  for (const series of seriesList) {
+    const datapoints = series.datapoints;
+    const seriesName = series.label;
 
     // Slice series into X axis buckets
     // |    | ** |    |  * |  **|
@@ -224,7 +224,7 @@ function convertToHeatMap(seriesList, yBucketSize, xBucketSize, logBase = 1) {
     // |____|____|____|____|____|_
     //
     _.forEach(datapoints, point => {
-      let bucketBound = getBucketBound(point[TIME_INDEX], xBucketSize);
+      const bucketBound = getBucketBound(point[TIME_INDEX], xBucketSize);
       pushToXBuckets(heatmap, point, bucketBound, seriesName);
     });
   }
@@ -247,13 +247,13 @@ function convertToHeatMap(seriesList, yBucketSize, xBucketSize, logBase = 1) {
 }
 
 function pushToXBuckets(buckets, point, bucketNum, seriesName) {
-  let value = point[VALUE_INDEX];
+  const value = point[VALUE_INDEX];
   if (value === null || value === undefined || isNaN(value)) {
     return;
   }
 
   // Add series name to point for future identification
-  let point_ext = _.concat(point, seriesName);
+  const point_ext = _.concat(point, seriesName);
 
   if (buckets[bucketNum] && buckets[bucketNum].values) {
     buckets[bucketNum].values.push(value);
@@ -308,18 +308,18 @@ function getBucketBounds(value, bucketSize) {
 }
 
 function getBucketBound(value, bucketSize) {
-  let bounds = getBucketBounds(value, bucketSize);
+  const bounds = getBucketBounds(value, bucketSize);
   return bounds.bottom;
 }
 
 function convertToValueBuckets(xBucket, bucketSize) {
-  let values = xBucket.values;
-  let points = xBucket.points;
-  let buckets = {};
+  const values = xBucket.values;
+  const points = xBucket.points;
+  const buckets = {};
 
   _.forEach(values, (val, index) => {
-    let bounds = getBucketBounds(val, bucketSize);
-    let bucketNum = bounds.bottom;
+    const bounds = getBucketBounds(val, bucketSize);
+    const bucketNum = bounds.bottom;
     pushToYBuckets(buckets, bucketNum, val, points[index], bounds);
   });
 
@@ -335,13 +335,13 @@ function getLogScaleBucketBounds(value, yBucketSplitFactor, logBase) {
     return { bottom: 0, top: 0 };
   }
 
-  let value_log = logp(value, logBase);
+  const value_log = logp(value, logBase);
   let pow, powTop;
   if (yBucketSplitFactor === 1 || !yBucketSplitFactor) {
     pow = Math.floor(value_log);
     powTop = pow + 1;
   } else {
-    let additional_bucket_size = 1 / yBucketSplitFactor;
+    const additional_bucket_size = 1 / yBucketSplitFactor;
     let additional_log = value_log - Math.floor(value_log);
     additional_log = Math.floor(additional_log / additional_bucket_size) * additional_bucket_size;
     pow = Math.floor(value_log) + additional_log;
@@ -354,18 +354,18 @@ function getLogScaleBucketBounds(value, yBucketSplitFactor, logBase) {
 }
 
 function getLogScaleBucketBound(value, yBucketSplitFactor, logBase) {
-  let bounds = getLogScaleBucketBounds(value, yBucketSplitFactor, logBase);
+  const bounds = getLogScaleBucketBounds(value, yBucketSplitFactor, logBase);
   return bounds.bottom;
 }
 
 function convertToLogScaleValueBuckets(xBucket, yBucketSplitFactor, logBase) {
-  let values = xBucket.values;
-  let points = xBucket.points;
+  const values = xBucket.values;
+  const points = xBucket.points;
 
-  let buckets = {};
+  const buckets = {};
   _.forEach(values, (val, index) => {
-    let bounds = getLogScaleBucketBounds(val, yBucketSplitFactor, logBase);
-    let bucketNum = bounds.bottom;
+    const bounds = getLogScaleBucketBounds(val, yBucketSplitFactor, logBase);
+    const bucketNum = bounds.bottom;
     pushToYBuckets(buckets, bucketNum, val, points[index], bounds);
   });
 
@@ -396,7 +396,7 @@ function calculateBucketSize(bounds: number[], logBase = 1): number {
   } else {
     bounds = _.sortBy(bounds);
     for (let i = 1; i < bounds.length; i++) {
-      let distance = getDistance(bounds[i], bounds[i - 1], logBase);
+      const distance = getDistance(bounds[i], bounds[i - 1], logBase);
       bucketSize = distance < bucketSize ? distance : bucketSize;
     }
   }
@@ -416,7 +416,7 @@ function getDistance(a: number, b: number, logBase = 1): number {
     return Math.abs(b - a);
   } else {
     // logarithmic distance
-    let ratio = Math.max(a, b) / Math.min(a, b);
+    const ratio = Math.max(a, b) / Math.min(a, b);
     return logp(ratio, logBase);
   }
 }
diff --git a/public/app/plugins/panel/heatmap/heatmap_tooltip.ts b/public/app/plugins/panel/heatmap/heatmap_tooltip.ts
index 6cf9262f520..5e48849ca59 100644
--- a/public/app/plugins/panel/heatmap/heatmap_tooltip.ts
+++ b/public/app/plugins/panel/heatmap/heatmap_tooltip.ts
@@ -4,10 +4,10 @@ import _ from 'lodash';
 import kbn from 'app/core/utils/kbn';
 import { getValueBucketBound } from './heatmap_data_converter';
 
-let TOOLTIP_PADDING_X = 30;
-let TOOLTIP_PADDING_Y = 5;
-let HISTOGRAM_WIDTH = 160;
-let HISTOGRAM_HEIGHT = 40;
+const TOOLTIP_PADDING_X = 30;
+const TOOLTIP_PADDING_Y = 5;
+const HISTOGRAM_WIDTH = 160;
+const HISTOGRAM_HEIGHT = 40;
 
 export class HeatmapTooltip {
   tooltip: any;
@@ -67,7 +67,7 @@ export class HeatmapTooltip {
       return;
     }
 
-    let { xBucketIndex, yBucketIndex } = this.getBucketIndexes(pos, data);
+    const { xBucketIndex, yBucketIndex } = this.getBucketIndexes(pos, data);
 
     if (!data.buckets[xBucketIndex]) {
       this.destroy();
@@ -79,14 +79,14 @@ export class HeatmapTooltip {
     }
 
     let boundBottom, boundTop, valuesNumber;
-    let xData = data.buckets[xBucketIndex];
+    const xData = data.buckets[xBucketIndex];
     // Search in special 'zero' bucket also
-    let yData = _.find(xData.buckets, (bucket, bucketIndex) => {
+    const yData = _.find(xData.buckets, (bucket, bucketIndex) => {
       return bucket.bounds.bottom === yBucketIndex || bucketIndex === yBucketIndex.toString();
     });
 
-    let tooltipTimeFormat = 'YYYY-MM-DD HH:mm:ss';
-    let time = this.dashboard.formatDate(xData.x, tooltipTimeFormat);
+    const tooltipTimeFormat = 'YYYY-MM-DD HH:mm:ss';
+    const time = this.dashboard.formatDate(xData.x, tooltipTimeFormat);
 
     // Decimals override. Code from panel/graph/graph.ts
     let countValueFormatter, bucketBoundFormatter;
@@ -97,7 +97,7 @@ export class HeatmapTooltip {
       // auto decimals
       // legend and tooltip gets one more decimal precision
       // than graph legend ticks
-      let decimals = (this.panelCtrl.decimals || -1) + 1;
+      const decimals = (this.panelCtrl.decimals || -1) + 1;
       countValueFormatter = this.countValueFormatter(decimals, this.panelCtrl.scaledDecimals + 2);
       bucketBoundFormatter = this.panelCtrl.tickValueFormatter(decimals, this.panelCtrl.scaledDecimals + 2);
     }
@@ -117,7 +117,7 @@ export class HeatmapTooltip {
           boundTop = yBucketIndex < data.tsBuckets.length - 1 ? tickFormatter(yBucketIndex + 1) : '';
         } else {
           // Display 0 if bucket is a special 'zero' bucket
-          let bottom = yData.y ? yData.bounds.bottom : 0;
+          const bottom = yData.y ? yData.bounds.bottom : 0;
           boundBottom = bucketBoundFormatter(bottom);
           boundTop = bucketBoundFormatter(yData.bounds.top);
         }
@@ -158,7 +158,7 @@ export class HeatmapTooltip {
   getXBucketIndex(x, data) {
     // First try to find X bucket by checking x pos is in the
     // [bucket.x, bucket.x + xBucketSize] interval
-    let xBucket = _.find(data.buckets, bucket => {
+    const xBucket = _.find(data.buckets, bucket => {
       return x > bucket.x && x - bucket.x <= data.xBucketSize;
     });
     return xBucket ? xBucket.x : getValueBucketBound(x, data.xBucketSize, 1);
@@ -168,7 +168,7 @@ export class HeatmapTooltip {
     if (data.tsBuckets) {
       return Math.floor(y);
     }
-    let yBucketIndex = getValueBucketBound(y, data.yBucketSize, this.panel.yAxis.logBase);
+    const yBucketIndex = getValueBucketBound(y, data.yBucketSize, this.panel.yAxis.logBase);
     return yBucketIndex;
   }
 
@@ -180,8 +180,8 @@ export class HeatmapTooltip {
   }
 
   addHistogram(data) {
-    let xBucket = this.scope.ctrl.data.buckets[data.x];
-    let yBucketSize = this.scope.ctrl.data.yBucketSize;
+    const xBucket = this.scope.ctrl.data.buckets[data.x];
+    const yBucketSize = this.scope.ctrl.data.yBucketSize;
     let min, max, ticks;
     if (this.scope.ctrl.data.tsBuckets) {
       min = 0;
@@ -193,33 +193,33 @@ export class HeatmapTooltip {
       ticks = this.scope.ctrl.data.yAxis.ticks;
     }
     let histogramData = _.map(xBucket.buckets, bucket => {
-      let count = bucket.count !== undefined ? bucket.count : bucket.values.length;
+      const count = bucket.count !== undefined ? bucket.count : bucket.values.length;
       return [bucket.bounds.bottom, count];
     });
     histogramData = _.filter(histogramData, d => {
       return d[0] >= min && d[0] <= max;
     });
 
-    let scale = this.scope.yScale.copy();
-    let histXScale = scale.domain([min, max]).range([0, HISTOGRAM_WIDTH]);
+    const scale = this.scope.yScale.copy();
+    const histXScale = scale.domain([min, max]).range([0, HISTOGRAM_WIDTH]);
 
     let barWidth;
     if (this.panel.yAxis.logBase === 1) {
       barWidth = Math.floor(HISTOGRAM_WIDTH / (max - min) * yBucketSize * 0.9);
     } else {
-      let barNumberFactor = yBucketSize ? yBucketSize : 1;
+      const barNumberFactor = yBucketSize ? yBucketSize : 1;
       barWidth = Math.floor(HISTOGRAM_WIDTH / ticks / barNumberFactor * 0.9);
     }
     barWidth = Math.max(barWidth, 1);
 
     // Normalize histogram Y axis
-    let histogramDomain = _.reduce(_.map(histogramData, d => d[1]), (sum, val) => sum + val, 0);
-    let histYScale = d3
+    const histogramDomain = _.reduce(_.map(histogramData, d => d[1]), (sum, val) => sum + val, 0);
+    const histYScale = d3
       .scaleLinear()
       .domain([0, histogramDomain])
       .range([0, HISTOGRAM_HEIGHT]);
 
-    let histogram = this.tooltip
+    const histogram = this.tooltip
       .select('.heatmap-histogram')
       .append('svg')
       .attr('width', HISTOGRAM_WIDTH)
@@ -247,9 +247,9 @@ export class HeatmapTooltip {
       return;
     }
 
-    let elem = $(this.tooltip.node())[0];
-    let tooltipWidth = elem.clientWidth;
-    let tooltipHeight = elem.clientHeight;
+    const elem = $(this.tooltip.node())[0];
+    const tooltipWidth = elem.clientWidth;
+    const tooltipHeight = elem.clientHeight;
 
     let left = pos.pageX + TOOLTIP_PADDING_X;
     let top = pos.pageY + TOOLTIP_PADDING_Y;
@@ -266,7 +266,7 @@ export class HeatmapTooltip {
   }
 
   countValueFormatter(decimals, scaledDecimals = null) {
-    let format = 'short';
+    const format = 'short';
     return function(value) {
       return kbn.valueFormats[format](value, decimals, scaledDecimals);
     };
diff --git a/public/app/plugins/panel/heatmap/rendering.ts b/public/app/plugins/panel/heatmap/rendering.ts
index 8ea216be89d..fcbb39f8417 100644
--- a/public/app/plugins/panel/heatmap/rendering.ts
+++ b/public/app/plugins/panel/heatmap/rendering.ts
@@ -9,7 +9,7 @@ import { HeatmapTooltip } from './heatmap_tooltip';
 import { mergeZeroBuckets } from './heatmap_data_converter';
 import { getColorScale, getOpacityScale } from './color_scale';
 
-let MIN_CARD_SIZE = 1,
+const MIN_CARD_SIZE = 1,
   CARD_PADDING = 1,
   CARD_ROUND = 0,
   DATA_RANGE_WIDING_FACTOR = 1.2,
@@ -117,8 +117,8 @@ export class HeatmapRenderer {
   }
 
   getYAxisWidth(elem) {
-    let axis_text = elem.selectAll('.axis-y text').nodes();
-    let max_text_width = _.max(
+    const axis_text = elem.selectAll('.axis-y text').nodes();
+    const max_text_width = _.max(
       _.map(axis_text, text => {
         // Use SVG getBBox method
         return text.getBBox().width;
@@ -129,10 +129,10 @@ export class HeatmapRenderer {
   }
 
   getXAxisHeight(elem) {
-    let axis_line = elem.select('.axis-x line');
+    const axis_line = elem.select('.axis-x line');
     if (!axis_line.empty()) {
-      let axis_line_position = parseFloat(elem.select('.axis-x line').attr('y2'));
-      let canvas_width = parseFloat(elem.attr('height'));
+      const axis_line_position = parseFloat(elem.select('.axis-x line').attr('y2'));
+      const canvas_width = parseFloat(elem.attr('height'));
       return canvas_width - axis_line_position;
     } else {
       // Default height
@@ -146,25 +146,25 @@ export class HeatmapRenderer {
       .domain([this.timeRange.from, this.timeRange.to])
       .range([0, this.chartWidth]);
 
-    let ticks = this.chartWidth / DEFAULT_X_TICK_SIZE_PX;
-    let grafanaTimeFormatter = ticksUtils.grafanaTimeFormat(ticks, this.timeRange.from, this.timeRange.to);
+    const ticks = this.chartWidth / DEFAULT_X_TICK_SIZE_PX;
+    const grafanaTimeFormatter = ticksUtils.grafanaTimeFormat(ticks, this.timeRange.from, this.timeRange.to);
     let timeFormat;
-    let dashboardTimeZone = this.ctrl.dashboard.getTimezone();
+    const dashboardTimeZone = this.ctrl.dashboard.getTimezone();
     if (dashboardTimeZone === 'utc') {
       timeFormat = d3.utcFormat(grafanaTimeFormatter);
     } else {
       timeFormat = d3.timeFormat(grafanaTimeFormatter);
     }
 
-    let xAxis = d3
+    const xAxis = d3
       .axisBottom(this.xScale)
       .ticks(ticks)
       .tickFormat(timeFormat)
       .tickPadding(X_AXIS_TICK_PADDING)
       .tickSize(this.chartHeight);
 
-    let posY = this.margin.top;
-    let posX = this.yAxisWidth;
+    const posY = this.margin.top;
+    const posX = this.yAxisWidth;
     this.heatmap
       .append('g')
       .attr('class', 'axis axis-x')
@@ -191,11 +191,11 @@ export class HeatmapRenderer {
     tick_interval = ticksUtils.tickStep(y_min, y_max, ticks);
     ticks = Math.ceil((y_max - y_min) / tick_interval);
 
-    let decimalsAuto = ticksUtils.getPrecision(tick_interval);
+    const decimalsAuto = ticksUtils.getPrecision(tick_interval);
     let decimals = this.panel.yAxis.decimals === null ? decimalsAuto : this.panel.yAxis.decimals;
     // Calculate scaledDecimals for log scales using tick size (as in jquery.flot.js)
-    let flot_tick_size = ticksUtils.getFlotTickSize(y_min, y_max, ticks, decimalsAuto);
-    let scaledDecimals = ticksUtils.getScaledDecimals(decimals, flot_tick_size);
+    const flot_tick_size = ticksUtils.getFlotTickSize(y_min, y_max, ticks, decimalsAuto);
+    const scaledDecimals = ticksUtils.getScaledDecimals(decimals, flot_tick_size);
     this.ctrl.decimals = decimals;
     this.ctrl.scaledDecimals = scaledDecimals;
 
@@ -218,7 +218,7 @@ export class HeatmapRenderer {
       .domain([y_min, y_max])
       .range([this.chartHeight, 0]);
 
-    let yAxis = d3
+    const yAxis = d3
       .axisLeft(this.yScale)
       .ticks(ticks)
       .tickFormat(this.tickValueFormatter(decimals, scaledDecimals))
@@ -232,8 +232,8 @@ export class HeatmapRenderer {
       .call(yAxis);
 
     // Calculate Y axis width first, then move axis into visible area
-    let posY = this.margin.top;
-    let posX = this.getYAxisWidth(this.heatmap) + Y_AXIS_TICK_PADDING;
+    const posY = this.margin.top;
+    const posX = this.getYAxisWidth(this.heatmap) + Y_AXIS_TICK_PADDING;
     this.heatmap.select('.axis-y').attr('transform', 'translate(' + posX + ',' + posY + ')');
 
     // Remove vertical line in the right of axis labels (called domain in d3)
@@ -245,7 +245,7 @@ export class HeatmapRenderer {
 
   // Wide Y values range and anjust to bucket size
   wideYAxisRange(min, max, tickInterval) {
-    let y_widing = (max * (this.dataRangeWidingFactor - 1) - min * (this.dataRangeWidingFactor - 1)) / 2;
+    const y_widing = (max * (this.dataRangeWidingFactor - 1) - min * (this.dataRangeWidingFactor - 1)) / 2;
     let y_min, y_max;
 
     if (tickInterval === 0) {
@@ -266,7 +266,7 @@ export class HeatmapRenderer {
   }
 
   addLogYAxis() {
-    let log_base = this.panel.yAxis.logBase;
+    const log_base = this.panel.yAxis.logBase;
     let { y_min, y_max } = this.adjustLogRange(this.data.heatmapStats.minLog, this.data.heatmapStats.max, log_base);
 
     y_min =
@@ -285,15 +285,15 @@ export class HeatmapRenderer {
       .domain([y_min, y_max])
       .range([this.chartHeight, 0]);
 
-    let domain = this.yScale.domain();
-    let tick_values = this.logScaleTickValues(domain, log_base);
+    const domain = this.yScale.domain();
+    const tick_values = this.logScaleTickValues(domain, log_base);
 
-    let decimalsAuto = ticksUtils.getPrecision(y_min);
-    let decimals = this.panel.yAxis.decimals || decimalsAuto;
+    const decimalsAuto = ticksUtils.getPrecision(y_min);
+    const decimals = this.panel.yAxis.decimals || decimalsAuto;
 
     // Calculate scaledDecimals for log scales using tick size (as in jquery.flot.js)
-    let flot_tick_size = ticksUtils.getFlotTickSize(y_min, y_max, tick_values.length, decimalsAuto);
-    let scaledDecimals = ticksUtils.getScaledDecimals(decimals, flot_tick_size);
+    const flot_tick_size = ticksUtils.getFlotTickSize(y_min, y_max, tick_values.length, decimalsAuto);
+    const scaledDecimals = ticksUtils.getScaledDecimals(decimals, flot_tick_size);
     this.ctrl.decimals = decimals;
     this.ctrl.scaledDecimals = scaledDecimals;
 
@@ -303,7 +303,7 @@ export class HeatmapRenderer {
       ticks: tick_values.length,
     };
 
-    let yAxis = d3
+    const yAxis = d3
       .axisLeft(this.yScale)
       .tickValues(tick_values)
       .tickFormat(this.tickValueFormatter(decimals, scaledDecimals))
@@ -317,8 +317,8 @@ export class HeatmapRenderer {
       .call(yAxis);
 
     // Calculate Y axis width first, then move axis into visible area
-    let posY = this.margin.top;
-    let posX = this.getYAxisWidth(this.heatmap) + Y_AXIS_TICK_PADDING;
+    const posY = this.margin.top;
+    const posX = this.getYAxisWidth(this.heatmap) + Y_AXIS_TICK_PADDING;
     this.heatmap.select('.axis-y').attr('transform', 'translate(' + posX + ',' + posY + ')');
 
     // Set first tick as pseudo 0
@@ -349,7 +349,7 @@ export class HeatmapRenderer {
     const decimals = this.panel.yAxis.decimals === null ? decimalsAuto : this.panel.yAxis.decimals;
     this.ctrl.decimals = decimals;
 
-    let tickValueFormatter = this.tickValueFormatter.bind(this);
+    const tickValueFormatter = this.tickValueFormatter.bind(this);
     function tickFormatter(valIndex) {
       let valueFormatted = tsBuckets[valIndex];
       if (!_.isNaN(_.toNumber(valueFormatted)) && valueFormatted !== '') {
@@ -362,7 +362,7 @@ export class HeatmapRenderer {
     const tsBucketsFormatted = _.map(tsBuckets, (v, i) => tickFormatter(i));
     this.data.tsBucketsFormatted = tsBucketsFormatted;
 
-    let yAxis = d3
+    const yAxis = d3
       .axisLeft(this.yScale)
       .tickValues(tick_values)
       .tickFormat(tickFormatter)
@@ -413,21 +413,21 @@ export class HeatmapRenderer {
   }
 
   logScaleTickValues(domain, base) {
-    let domainMin = domain[0];
-    let domainMax = domain[1];
-    let tickValues = [];
+    const domainMin = domain[0];
+    const domainMax = domain[1];
+    const tickValues = [];
 
     if (domainMin < 1) {
-      let under_one_ticks = Math.floor(ticksUtils.logp(domainMin, base));
+      const under_one_ticks = Math.floor(ticksUtils.logp(domainMin, base));
       for (let i = under_one_ticks; i < 0; i++) {
-        let tick_value = Math.pow(base, i);
+        const tick_value = Math.pow(base, i);
         tickValues.push(tick_value);
       }
     }
 
-    let ticks = Math.ceil(ticksUtils.logp(domainMax, base));
+    const ticks = Math.ceil(ticksUtils.logp(domainMax, base));
     for (let i = 0; i <= ticks; i++) {
-      let tick_value = Math.pow(base, i);
+      const tick_value = Math.pow(base, i);
       tickValues.push(tick_value);
     }
 
@@ -435,7 +435,7 @@ export class HeatmapRenderer {
   }
 
   tickValueFormatter(decimals, scaledDecimals = null) {
-    let format = this.panel.yAxis.format;
+    const format = this.panel.yAxis.format;
     return function(value) {
       try {
         return format !== 'none' ? kbn.valueFormats[format](value, decimals, scaledDecimals) : value;
@@ -490,7 +490,7 @@ export class HeatmapRenderer {
   }
 
   addHeatmapCanvas() {
-    let heatmap_elem = this.$heatmap[0];
+    const heatmap_elem = this.$heatmap[0];
 
     this.width = Math.floor(this.$heatmap.width()) - this.padding.right;
     this.height = Math.floor(this.$heatmap.height()) - this.padding.bottom;
@@ -514,18 +514,18 @@ export class HeatmapRenderer {
     this.addAxes();
 
     if (this.panel.yAxis.logBase !== 1 && this.panel.dataFormat !== 'tsbuckets') {
-      let log_base = this.panel.yAxis.logBase;
-      let domain = this.yScale.domain();
-      let tick_values = this.logScaleTickValues(domain, log_base);
+      const log_base = this.panel.yAxis.logBase;
+      const domain = this.yScale.domain();
+      const tick_values = this.logScaleTickValues(domain, log_base);
       this.data.buckets = mergeZeroBuckets(this.data.buckets, _.min(tick_values));
     }
 
-    let cardsData = this.data.cards;
-    let maxValueAuto = this.data.cardStats.max;
-    let maxValue = this.panel.color.max || maxValueAuto;
-    let minValue = this.panel.color.min || 0;
+    const cardsData = this.data.cards;
+    const maxValueAuto = this.data.cardStats.max;
+    const maxValue = this.panel.color.max || maxValueAuto;
+    const minValue = this.panel.color.min || 0;
 
-    let colorScheme = _.find(this.ctrl.colorSchemes, {
+    const colorScheme = _.find(this.ctrl.colorSchemes, {
       value: this.panel.color.colorScheme,
     });
     this.colorScale = getColorScale(colorScheme, contextSrv.user.lightTheme, maxValue, minValue);
@@ -549,7 +549,7 @@ export class HeatmapRenderer {
       .style('stroke-width', 0)
       .style('opacity', this.getCardOpacity.bind(this));
 
-    let $cards = this.$heatmap.find('.heatmap-card');
+    const $cards = this.$heatmap.find('.heatmap-card');
     $cards
       .on('mouseenter', event => {
         this.tooltip.mouseOverBucket = true;
@@ -562,10 +562,10 @@ export class HeatmapRenderer {
   }
 
   highlightCard(event) {
-    let color = d3.select(event.target).style('fill');
-    let highlightColor = d3.color(color).darker(2);
-    let strokeColor = d3.color(color).brighter(4);
-    let current_card = d3.select(event.target);
+    const color = d3.select(event.target).style('fill');
+    const highlightColor = d3.color(color).darker(2);
+    const strokeColor = d3.color(color).brighter(4);
+    const current_card = d3.select(event.target);
     this.tooltip.originalFillColor = color;
     current_card
       .style('fill', highlightColor.toString())
@@ -582,12 +582,12 @@ export class HeatmapRenderer {
   }
 
   setCardSize() {
-    let xGridSize = Math.floor(this.xScale(this.data.xBucketSize) - this.xScale(0));
+    const xGridSize = Math.floor(this.xScale(this.data.xBucketSize) - this.xScale(0));
     let yGridSize = Math.floor(this.yScale(this.yScale.invert(0) - this.data.yBucketSize));
 
     if (this.panel.yAxis.logBase !== 1) {
-      let base = this.panel.yAxis.logBase;
-      let splitFactor = this.data.yBucketSize || 1;
+      const base = this.panel.yAxis.logBase;
+      const splitFactor = this.data.yBucketSize || 1;
       yGridSize = Math.floor((this.yScale(1) - this.yScale(base)) / splitFactor);
     }
 
@@ -611,7 +611,7 @@ export class HeatmapRenderer {
     let w;
     if (this.xScale(d.x) < 0) {
       // Cut card left to prevent overlay
-      let cutted_width = this.xScale(d.x) + this.cardWidth;
+      const cutted_width = this.xScale(d.x) + this.cardWidth;
       w = cutted_width > 0 ? cutted_width : 0;
     } else if (this.xScale(d.x) + this.cardWidth > this.chartWidth) {
       // Cut card right to prevent overlay
@@ -639,7 +639,7 @@ export class HeatmapRenderer {
   }
 
   getCardHeight(d) {
-    let y = this.yScale(d.y) + this.chartTop - this.cardHeight - this.cardPadding;
+    const y = this.yScale(d.y) + this.chartTop - this.cardHeight - this.cardPadding;
     let h = this.cardHeight;
 
     if (this.panel.yAxis.logBase !== 1 && d.y === 0) {
@@ -703,10 +703,10 @@ export class HeatmapRenderer {
     this.mouseUpHandler = null;
     this.selection.active = false;
 
-    let selectionRange = Math.abs(this.selection.x2 - this.selection.x1);
+    const selectionRange = Math.abs(this.selection.x2 - this.selection.x1);
     if (this.selection.x2 >= 0 && selectionRange > MIN_SELECTION_WIDTH) {
-      let timeFrom = this.xScale.invert(Math.min(this.selection.x1, this.selection.x2) - this.yAxisWidth);
-      let timeTo = this.xScale.invert(Math.max(this.selection.x1, this.selection.x2) - this.yAxisWidth);
+      const timeFrom = this.xScale.invert(Math.min(this.selection.x1, this.selection.x2) - this.yAxisWidth);
+      const timeTo = this.xScale.invert(Math.max(this.selection.x1, this.selection.x2) - this.yAxisWidth);
 
       this.ctrl.timeSrv.setTime({
         from: moment.utc(timeFrom),
@@ -744,9 +744,9 @@ export class HeatmapRenderer {
   }
 
   getEventPos(event, offset) {
-    let x = this.xScale.invert(offset.x - this.yAxisWidth).valueOf();
-    let y = this.yScale.invert(offset.y - this.chartTop);
-    let pos = {
+    const x = this.xScale.invert(offset.x - this.yAxisWidth).valueOf();
+    const y = this.yScale.invert(offset.y - this.chartTop);
+    const pos = {
       pageX: event.pageX,
       pageY: event.pageY,
       x: x,
@@ -776,8 +776,8 @@ export class HeatmapRenderer {
   drawSelection(posX1, posX2) {
     if (this.heatmap) {
       this.heatmap.selectAll('.heatmap-selection').remove();
-      let selectionX = Math.min(posX1, posX2);
-      let selectionWidth = Math.abs(posX1 - posX2);
+      const selectionX = Math.min(posX1, posX2);
+      const selectionWidth = Math.abs(posX1 - posX2);
 
       if (selectionWidth > MIN_SELECTION_WIDTH) {
         this.heatmap
@@ -823,7 +823,7 @@ export class HeatmapRenderer {
 
   drawSharedCrosshair(pos) {
     if (this.heatmap && this.ctrl.dashboard.graphTooltip !== 0) {
-      let posX = this.xScale(pos.x) + this.yAxisWidth;
+      const posX = this.xScale(pos.x) + this.yAxisWidth;
       this.drawCrosshair(posX);
     }
   }
diff --git a/public/app/plugins/panel/heatmap/specs/heatmap_ctrl.test.ts b/public/app/plugins/panel/heatmap/specs/heatmap_ctrl.test.ts
index 800c2518f9a..d9d929a2697 100644
--- a/public/app/plugins/panel/heatmap/specs/heatmap_ctrl.test.ts
+++ b/public/app/plugins/panel/heatmap/specs/heatmap_ctrl.test.ts
@@ -2,13 +2,13 @@ import moment from 'moment';
 import { HeatmapCtrl } from '../heatmap_ctrl';
 
 describe('HeatmapCtrl', function() {
-  let ctx = <any>{};
+  const ctx = <any>{};
 
-  let $injector = {
+  const $injector = {
     get: () => {},
   };
 
-  let $scope = {
+  const $scope = {
     $on: () => {},
   };
 
diff --git a/public/app/plugins/panel/heatmap/specs/heatmap_data_converter.test.ts b/public/app/plugins/panel/heatmap/specs/heatmap_data_converter.test.ts
index b6a8713a3e9..1c8a7a32caf 100644
--- a/public/app/plugins/panel/heatmap/specs/heatmap_data_converter.test.ts
+++ b/public/app/plugins/panel/heatmap/specs/heatmap_data_converter.test.ts
@@ -10,7 +10,7 @@ import {
 } from '../heatmap_data_converter';
 
 describe('isHeatmapDataEqual', () => {
-  let ctx: any = {};
+  const ctx: any = {};
 
   beforeEach(() => {
     ctx.heatmapA = {
@@ -35,17 +35,17 @@ describe('isHeatmapDataEqual', () => {
   });
 
   it('should proper compare objects', () => {
-    let heatmapC = _.cloneDeep(ctx.heatmapA);
+    const heatmapC = _.cloneDeep(ctx.heatmapA);
     heatmapC['1422774000000'].buckets['1'].values = [1, 1.5];
 
-    let heatmapD = _.cloneDeep(ctx.heatmapA);
+    const heatmapD = _.cloneDeep(ctx.heatmapA);
     heatmapD['1422774000000'].buckets['1'].values = [1.5, 1, 1.6];
 
-    let heatmapE = _.cloneDeep(ctx.heatmapA);
+    const heatmapE = _.cloneDeep(ctx.heatmapA);
     heatmapE['1422774000000'].buckets['1'].values = [1, 1.6];
 
-    let empty = {};
-    let emptyValues = _.cloneDeep(ctx.heatmapA);
+    const empty = {};
+    const emptyValues = _.cloneDeep(ctx.heatmapA);
     emptyValues['1422774000000'].buckets['1'].values = [];
 
     expect(isHeatmapDataEqual(ctx.heatmapA, ctx.heatmapB)).toBe(true);
@@ -69,7 +69,7 @@ describe('isHeatmapDataEqual', () => {
 });
 
 describe('calculateBucketSize', () => {
-  let ctx: any = {};
+  const ctx: any = {};
 
   describe('when logBase is 1 (linear scale)', () => {
     beforeEach(() => {
@@ -88,7 +88,7 @@ describe('calculateBucketSize', () => {
 
     it('should properly calculate bucket size', () => {
       _.each(ctx.bounds_set, b => {
-        let bucketSize = calculateBucketSize(b.bounds, ctx.logBase);
+        const bucketSize = calculateBucketSize(b.bounds, ctx.logBase);
         expect(bucketSize).toBe(b.size);
       });
     });
@@ -108,7 +108,7 @@ describe('calculateBucketSize', () => {
 
     it('should properly calculate bucket size', () => {
       _.each(ctx.bounds_set, b => {
-        let bucketSize = calculateBucketSize(b.bounds, ctx.logBase);
+        const bucketSize = calculateBucketSize(b.bounds, ctx.logBase);
         expect(isEqual(bucketSize, b.size)).toBe(true);
       });
     });
@@ -116,7 +116,7 @@ describe('calculateBucketSize', () => {
 });
 
 describe('HeatmapDataConverter', () => {
-  let ctx: any = {};
+  const ctx: any = {};
 
   beforeEach(() => {
     ctx.series = [];
@@ -150,7 +150,7 @@ describe('HeatmapDataConverter', () => {
     });
 
     it('should build proper heatmap data', () => {
-      let expectedHeatmap = {
+      const expectedHeatmap = {
         '1422774000000': {
           x: 1422774000000,
           buckets: {
@@ -183,7 +183,7 @@ describe('HeatmapDataConverter', () => {
         },
       };
 
-      let heatmap = convertToHeatMap(ctx.series, ctx.yBucketSize, ctx.xBucketSize, ctx.logBase);
+      const heatmap = convertToHeatMap(ctx.series, ctx.yBucketSize, ctx.xBucketSize, ctx.logBase);
       expect(isHeatmapDataEqual(heatmap, expectedHeatmap)).toBe(true);
     });
   });
@@ -194,7 +194,7 @@ describe('HeatmapDataConverter', () => {
     });
 
     it('should build proper heatmap data', () => {
-      let expectedHeatmap = {
+      const expectedHeatmap = {
         '1422774000000': {
           x: 1422774000000,
           buckets: {
@@ -210,14 +210,14 @@ describe('HeatmapDataConverter', () => {
         },
       };
 
-      let heatmap = convertToHeatMap(ctx.series, ctx.yBucketSize, ctx.xBucketSize, ctx.logBase);
+      const heatmap = convertToHeatMap(ctx.series, ctx.yBucketSize, ctx.xBucketSize, ctx.logBase);
       expect(isHeatmapDataEqual(heatmap, expectedHeatmap)).toBe(true);
     });
   });
 });
 
 describe('Histogram converter', () => {
-  let ctx: any = {};
+  const ctx: any = {};
 
   beforeEach(() => {
     ctx.series = [];
@@ -248,7 +248,7 @@ describe('Histogram converter', () => {
     beforeEach(() => {});
 
     it('should build proper heatmap data', () => {
-      let expectedHeatmap = {
+      const expectedHeatmap = {
         '1422774000000': {
           x: 1422774000000,
           buckets: {
@@ -343,18 +343,18 @@ describe('convertToCards', () => {
   });
 
   it('should build proper cards data', () => {
-    let expectedCards = [
+    const expectedCards = [
       { x: 1422774000000, y: 1, count: 1, values: [1], yBounds: {} },
       { x: 1422774000000, y: 2, count: 1, values: [2], yBounds: {} },
       { x: 1422774060000, y: 2, count: 2, values: [2, 3], yBounds: {} },
     ];
-    let res = convertToCards(buckets);
+    const res = convertToCards(buckets);
     expect(res.cards).toMatchObject(expectedCards);
   });
 
   it('should build proper cards stats', () => {
-    let expectedStats = { min: 1, max: 2 };
-    let res = convertToCards(buckets);
+    const expectedStats = { min: 1, max: 2 };
+    const res = convertToCards(buckets);
     expect(res.cardStats).toMatchObject(expectedStats);
   });
 });
diff --git a/public/app/plugins/panel/pluginlist/module.ts b/public/app/plugins/panel/pluginlist/module.ts
index acfa69b171c..93bf258f50d 100644
--- a/public/app/plugins/panel/pluginlist/module.ts
+++ b/public/app/plugins/panel/pluginlist/module.ts
@@ -60,7 +60,7 @@ class PluginListCtrl extends PanelCtrl {
       this.viewModel[1].list = _.filter(plugins, { type: 'panel' });
       this.viewModel[2].list = _.filter(plugins, { type: 'datasource' });
 
-      for (let plugin of this.pluginList) {
+      for (const plugin of this.pluginList) {
         if (plugin.hasUpdate) {
           plugin.state = 'has-update';
         } else if (!plugin.enabled) {
diff --git a/public/app/plugins/panel/singlestat/module.ts b/public/app/plugins/panel/singlestat/module.ts
index ebd2628b086..b858f77556f 100644
--- a/public/app/plugins/panel/singlestat/module.ts
+++ b/public/app/plugins/panel/singlestat/module.ts
@@ -293,8 +293,8 @@ class SingleStatCtrl extends MetricsPanelCtrl {
     }
 
     if (this.series && this.series.length > 0) {
-      let lastPoint = _.last(this.series[0].datapoints);
-      let lastValue = _.isArray(lastPoint) ? lastPoint[0] : null;
+      const lastPoint = _.last(this.series[0].datapoints);
+      const lastValue = _.isArray(lastPoint) ? lastPoint[0] : null;
 
       if (this.panel.valueName === 'name') {
         data.value = 0;
@@ -305,7 +305,7 @@ class SingleStatCtrl extends MetricsPanelCtrl {
         data.valueFormatted = _.escape(lastValue);
         data.valueRounded = 0;
       } else if (this.panel.valueName === 'last_time') {
-        let formatFunc = kbn.valueFormats[this.panel.format];
+        const formatFunc = kbn.valueFormats[this.panel.format];
         data.value = lastPoint[1];
         data.valueRounded = data.value;
         data.valueFormatted = formatFunc(data.value, this.dashboard.isTimezoneUtc());
@@ -313,8 +313,8 @@ class SingleStatCtrl extends MetricsPanelCtrl {
         data.value = this.series[0].stats[this.panel.valueName];
         data.flotpairs = this.series[0].flotpairs;
 
-        let decimalInfo = this.getDecimalsForValue(data.value);
-        let formatFunc = kbn.valueFormats[this.panel.format];
+        const decimalInfo = this.getDecimalsForValue(data.value);
+        const formatFunc = kbn.valueFormats[this.panel.format];
         data.valueFormatted = formatFunc(data.value, decimalInfo.decimals, decimalInfo.scaledDecimals);
         data.valueRounded = kbn.roundValue(data.value, decimalInfo.decimals);
       }
@@ -330,7 +330,7 @@ class SingleStatCtrl extends MetricsPanelCtrl {
     // check value to text mappings if its enabled
     if (this.panel.mappingType === 1) {
       for (let i = 0; i < this.panel.valueMaps.length; i++) {
-        let map = this.panel.valueMaps[i];
+        const map = this.panel.valueMaps[i];
         // special null case
         if (map.value === 'null') {
           if (data.value === null || data.value === void 0) {
@@ -349,7 +349,7 @@ class SingleStatCtrl extends MetricsPanelCtrl {
       }
     } else if (this.panel.mappingType === 2) {
       for (let i = 0; i < this.panel.rangeMaps.length; i++) {
-        let map = this.panel.rangeMaps[i];
+        const map = this.panel.rangeMaps[i];
         // special null case
         if (map.from === 'null' && map.to === 'null') {
           if (data.value === null || data.value === void 0) {
diff --git a/public/app/plugins/panel/singlestat/specs/singlestat.test.ts b/public/app/plugins/panel/singlestat/specs/singlestat.test.ts
index 0480d0be5c3..9d204f19f5b 100644
--- a/public/app/plugins/panel/singlestat/specs/singlestat.test.ts
+++ b/public/app/plugins/panel/singlestat/specs/singlestat.test.ts
@@ -2,15 +2,15 @@ import { SingleStatCtrl } from '../module';
 import moment from 'moment';
 
 describe('SingleStatCtrl', function() {
-  let ctx = <any>{};
-  let epoch = 1505826363746;
+  const ctx = <any>{};
+  const epoch = 1505826363746;
   Date.now = () => epoch;
 
-  let $scope = {
+  const $scope = {
     $on: () => {},
   };
 
-  let $injector = {
+  const $injector = {
     get: () => {},
   };
 
diff --git a/public/app/plugins/panel/table/module.ts b/public/app/plugins/panel/table/module.ts
index 03d92f7e48f..4169a25dd43 100644
--- a/public/app/plugins/panel/table/module.ts
+++ b/public/app/plugins/panel/table/module.ts
@@ -243,7 +243,7 @@ class TablePanelCtrl extends MetricsPanelCtrl {
     });
 
     function addFilterClicked(e) {
-      let filterData = $(e.currentTarget).data();
+      const filterData = $(e.currentTarget).data();
       var options = {
         datasource: panel.datasource,
         key: data.columns[filterData.column].text,
diff --git a/public/app/plugins/panel/table/renderer.ts b/public/app/plugins/panel/table/renderer.ts
index d85c20a87cc..d512c1335df 100644
--- a/public/app/plugins/panel/table/renderer.ts
+++ b/public/app/plugins/panel/table/renderer.ts
@@ -21,11 +21,11 @@ export class TableRenderer {
     this.colorState = {};
 
     for (let colIndex = 0; colIndex < this.table.columns.length; colIndex++) {
-      let column = this.table.columns[colIndex];
+      const column = this.table.columns[colIndex];
       column.title = column.text;
 
       for (let i = 0; i < this.panel.styles.length; i++) {
-        let style = this.panel.styles[i];
+        const style = this.panel.styles[i];
 
         var regex = kbn.stringToJsRegex(style.pattern);
         if (column.text.match(regex)) {
@@ -154,7 +154,7 @@ export class TableRenderer {
     }
 
     if (column.style.type === 'number') {
-      let valueFormatter = kbn.valueFormats[column.unit || column.style.unit];
+      const valueFormatter = kbn.valueFormats[column.unit || column.style.unit];
 
       return v => {
         if (v === null || v === void 0) {
@@ -193,9 +193,9 @@ export class TableRenderer {
   }
 
   renderRowVariables(rowIndex) {
-    let scopedVars = {};
+    const scopedVars = {};
     let cell_variable;
-    let row = this.table.rows[rowIndex];
+    const row = this.table.rows[rowIndex];
     for (let i = 0; i < row.length; i++) {
       cell_variable = `__cell_${i}`;
       scopedVars[cell_variable] = { value: row[i] };
@@ -288,15 +288,15 @@ export class TableRenderer {
   }
 
   render(page) {
-    let pageSize = this.panel.pageSize || 100;
-    let startPos = page * pageSize;
-    let endPos = Math.min(startPos + pageSize, this.table.rows.length);
+    const pageSize = this.panel.pageSize || 100;
+    const startPos = page * pageSize;
+    const endPos = Math.min(startPos + pageSize, this.table.rows.length);
     var html = '';
-    let rowClasses = [];
+    const rowClasses = [];
     let rowClass = '';
 
     for (var y = startPos; y < endPos; y++) {
-      let row = this.table.rows[y];
+      const row = this.table.rows[y];
       let cellHtml = '';
       let rowStyle = '';
       for (var i = 0; i < this.table.columns.length; i++) {
@@ -320,11 +320,11 @@ export class TableRenderer {
   }
 
   render_values() {
-    let rows = [];
+    const rows = [];
 
     for (var y = 0; y < this.table.rows.length; y++) {
-      let row = this.table.rows[y];
-      let new_row = [];
+      const row = this.table.rows[y];
+      const new_row = [];
       for (var i = 0; i < this.table.columns.length; i++) {
         new_row.push(this.formatColumnValue(i, row[i]));
       }
diff --git a/public/app/plugins/panel/table/transformers.ts b/public/app/plugins/panel/table/transformers.ts
index 1659ba3e3aa..840bfa83d5b 100644
--- a/public/app/plugins/panel/table/transformers.ts
+++ b/public/app/plugins/panel/table/transformers.ts
@@ -294,7 +294,7 @@ transformers['json'] = {
   transform: function(data, panel, model) {
     var i, y, z;
 
-    for (let column of panel.columns) {
+    for (const column of panel.columns) {
       var tableCol: any = { text: column.text };
 
       // if filterable data then set columns to filterable
diff --git a/public/app/stores/AlertListStore/AlertListStore.ts b/public/app/stores/AlertListStore/AlertListStore.ts
index ec27565a1a1..c2b9f5e4962 100644
--- a/public/app/stores/AlertListStore/AlertListStore.ts
+++ b/public/app/stores/AlertListStore/AlertListStore.ts
@@ -13,7 +13,7 @@ export const AlertListStore = types
   })
   .views(self => ({
     get filteredRules() {
-      let regex = new RegExp(self.search, 'i');
+      const regex = new RegExp(self.search, 'i');
       return self.rules.filter(alert => {
         return regex.test(alert.name) || regex.test(alert.stateText) || regex.test(alert.info);
       });
@@ -26,7 +26,7 @@ export const AlertListStore = types
       const apiRules = yield backendSrv.get('/api/alerts', filters);
       self.rules.clear();
 
-      for (let rule of apiRules) {
+      for (const rule of apiRules) {
         setStateFields(rule, rule.state);
 
         if (rule.state !== 'paused') {
diff --git a/public/app/stores/NavStore/NavStore.ts b/public/app/stores/NavStore/NavStore.ts
index bef53b828b6..d869b0f740d 100644
--- a/public/app/stores/NavStore/NavStore.ts
+++ b/public/app/stores/NavStore/NavStore.ts
@@ -12,9 +12,9 @@ export const NavStore = types
     load(...args) {
       let children = getEnv(self).navTree;
       let main, node;
-      let parents = [];
+      const parents = [];
 
-      for (let id of args) {
+      for (const id of args) {
         node = children.find(el => el.id === id);
 
         if (!node) {
@@ -28,7 +28,7 @@ export const NavStore = types
       main = parents[parents.length - 2];
 
       if (main.children) {
-        for (let item of main.children) {
+        for (const item of main.children) {
           item.active = false;
 
           if (item.url === node.url) {
@@ -42,7 +42,7 @@ export const NavStore = types
     },
 
     initFolderNav(folder: any, activeChildId: string) {
-      let main = {
+      const main = {
         icon: 'fa fa-folder-open',
         id: 'manage-folder',
         subTitle: 'Manage folder dashboards & permissions',
@@ -79,13 +79,13 @@ export const NavStore = types
 
     initDatasourceEditNav(ds: any, plugin: any, currentPage: string) {
       let title = 'New';
-      let subTitle = `Type: ${plugin.name}`;
+      const subTitle = `Type: ${plugin.name}`;
 
       if (ds.id) {
         title = ds.name;
       }
 
-      let main = {
+      const main = {
         img: plugin.info.logos.large,
         id: 'ds-edit-' + plugin.id,
         subTitle: subTitle,
@@ -118,7 +118,7 @@ export const NavStore = types
     },
 
     initTeamPage(team: Team, tab: string, isSyncEnabled: boolean) {
-      let main = {
+      const main = {
         img: team.avatarUrl,
         id: 'team-' + team.id,
         subTitle: 'Manage members & settings',
diff --git a/public/app/stores/PermissionsStore/PermissionsStore.ts b/public/app/stores/PermissionsStore/PermissionsStore.ts
index 95d63c8527a..d778a09443d 100644
--- a/public/app/stores/PermissionsStore/PermissionsStore.ts
+++ b/public/app/stores/PermissionsStore/PermissionsStore.ts
@@ -117,7 +117,7 @@ export const PermissionsStore = types
       }),
 
       addStoreItem: flow(function* addStoreItem() {
-        let item = {
+        const item = {
           type: self.newItem.type,
           permission: self.newItem.permission,
           dashboardId: self.dashboardId,
@@ -155,7 +155,7 @@ export const PermissionsStore = types
         try {
           yield updateItems(self, updatedItems);
           self.items.push(newItem);
-          let sortedItems = self.items.sort((a, b) => b.sortRank - a.sortRank || a.name.localeCompare(b.name));
+          const sortedItems = self.items.sort((a, b) => b.sortRank - a.sortRank || a.name.localeCompare(b.name));
           self.items = sortedItems;
           resetNewTypeInternal();
         } catch {}
@@ -197,7 +197,7 @@ export const PermissionsStore = types
 const updateItems = (self, items) => {
   const backendSrv = getEnv(self).backendSrv;
   const updated = [];
-  for (let item of items) {
+  for (const item of items) {
     if (item.inherited) {
       continue;
     }
diff --git a/public/app/stores/TeamsStore/TeamsStore.ts b/public/app/stores/TeamsStore/TeamsStore.ts
index 1aec4a1433c..f8e101163a2 100644
--- a/public/app/stores/TeamsStore/TeamsStore.ts
+++ b/public/app/stores/TeamsStore/TeamsStore.ts
@@ -32,8 +32,8 @@ export const TeamModel = types
   })
   .views(self => ({
     get filteredMembers() {
-      let members = this.members.values();
-      let regex = new RegExp(self.search, 'i');
+      const members = this.members.values();
+      const regex = new RegExp(self.search, 'i');
       return members.filter(member => {
         return regex.test(member.login) || regex.test(member.email);
       });
@@ -66,7 +66,7 @@ export const TeamModel = types
       const rsp = yield backendSrv.get(`/api/teams/${self.id}/members`);
       self.members.clear();
 
-      for (let member of rsp) {
+      for (const member of rsp) {
         self.members.set(member.userId.toString(), TeamMemberModel.create(member));
       }
     }),
@@ -88,7 +88,7 @@ export const TeamModel = types
       const rsp = yield backendSrv.get(`/api/teams/${self.id}/groups`);
       self.groups.clear();
 
-      for (let group of rsp) {
+      for (const group of rsp) {
         self.groups.set(group.groupId, TeamGroupModel.create(group));
       }
     }),
@@ -122,8 +122,8 @@ export const TeamsStore = types
   })
   .views(self => ({
     get filteredTeams() {
-      let teams = this.map.values();
-      let regex = new RegExp(self.search, 'i');
+      const teams = this.map.values();
+      const regex = new RegExp(self.search, 'i');
       return teams.filter(team => {
         return regex.test(team.name);
       });
@@ -135,7 +135,7 @@ export const TeamsStore = types
       const rsp = yield backendSrv.get('/api/teams/search/', { perpage: 50, page: 1 });
       self.map.clear();
 
-      for (let team of rsp.teams) {
+      for (const team of rsp.teams) {
         self.map.set(team.id.toString(), TeamModel.create(team));
       }
     }),
diff --git a/public/app/stores/ViewStore/ViewStore.ts b/public/app/stores/ViewStore/ViewStore.ts
index ba966a194d8..3af6737209c 100644
--- a/public/app/stores/ViewStore/ViewStore.ts
+++ b/public/app/stores/ViewStore/ViewStore.ts
@@ -25,7 +25,7 @@ export const ViewStore = types
     // querystring only
     function updateQuery(query: any) {
       self.query.clear();
-      for (let key of Object.keys(query)) {
+      for (const key of Object.keys(query)) {
         if (query[key]) {
           self.query.set(key, query[key]);
         }
@@ -35,7 +35,7 @@ export const ViewStore = types
     // needed to get route parameters like slug from the url
     function updateRouteParams(routeParams: any) {
       self.routeParams.clear();
-      for (let key of Object.keys(routeParams)) {
+      for (const key of Object.keys(routeParams)) {
         if (routeParams[key]) {
           self.routeParams.set(key, routeParams[key]);
         }
diff --git a/public/test/core/utils/version_test.ts b/public/test/core/utils/version_test.ts
index 20983cb32ec..91330389e24 100644
--- a/public/test/core/utils/version_test.ts
+++ b/public/test/core/utils/version_test.ts
@@ -1,11 +1,11 @@
-import {SemVersion, isVersionGtOrEq} from 'app/core/utils/version';
+import { SemVersion, isVersionGtOrEq } from 'app/core/utils/version';
 
-describe("SemVersion", () => {
+describe('SemVersion', () => {
   let version = '1.0.0-alpha.1';
 
   describe('parsing', () => {
     it('should parse version properly', () => {
-      let semver = new SemVersion(version);
+      const semver = new SemVersion(version);
       expect(semver.major).toBe(1);
       expect(semver.minor).toBe(0);
       expect(semver.patch).toBe(0);
@@ -19,15 +19,15 @@ describe("SemVersion", () => {
     });
 
     it('should detect greater version properly', () => {
-      let semver = new SemVersion(version);
-      let cases = [
-        {value: '3.4.5', expected: true},
-        {value: '3.4.4', expected: true},
-        {value: '3.4.6', expected: false},
-        {value: '4', expected: false},
-        {value: '3.5', expected: false},
+      const semver = new SemVersion(version);
+      const cases = [
+        { value: '3.4.5', expected: true },
+        { value: '3.4.4', expected: true },
+        { value: '3.4.6', expected: false },
+        { value: '4', expected: false },
+        { value: '3.5', expected: false },
       ];
-      cases.forEach((testCase) => {
+      cases.forEach(testCase => {
         expect(semver.isGtOrEq(testCase.value)).toBe(testCase.expected);
       });
     });
@@ -35,17 +35,17 @@ describe("SemVersion", () => {
 
   describe('isVersionGtOrEq', () => {
     it('should compare versions properly (a >= b)', () => {
-      let cases = [
-        {values: ['3.4.5', '3.4.5'], expected: true},
-        {values: ['3.4.5', '3.4.4'] , expected: true},
-        {values: ['3.4.5', '3.4.6'], expected: false},
-        {values: ['3.4', '3.4.0'], expected: true},
-        {values: ['3', '3.0.0'], expected: true},
-        {values: ['3.1.1-beta1', '3.1'], expected: true},
-        {values: ['3.4.5', '4'], expected: false},
-        {values: ['3.4.5', '3.5'], expected: false},
+      const cases = [
+        { values: ['3.4.5', '3.4.5'], expected: true },
+        { values: ['3.4.5', '3.4.4'], expected: true },
+        { values: ['3.4.5', '3.4.6'], expected: false },
+        { values: ['3.4', '3.4.0'], expected: true },
+        { values: ['3', '3.0.0'], expected: true },
+        { values: ['3.1.1-beta1', '3.1'], expected: true },
+        { values: ['3.4.5', '4'], expected: false },
+        { values: ['3.4.5', '3.5'], expected: false },
       ];
-      cases.forEach((testCase) => {
+      cases.forEach(testCase => {
         expect(isVersionGtOrEq(testCase.values[0], testCase.values[1])).toBe(testCase.expected);
       });
     });
diff --git a/public/test/index.ts b/public/test/index.ts
index 33f24331b67..05a47686775 100644
--- a/public/test/index.ts
+++ b/public/test/index.ts
@@ -22,10 +22,6 @@ angular.module('grafana.filters', []);
 angular.module('grafana.routes', ['ngRoute']);
 
 const context = (<any>require).context('../', true, /specs\.(tsx?|js)/);
-for (let key of context.keys()) {
+for (const key of context.keys()) {
   context(key);
 }
-
-
-
-
diff --git a/public/test/mocks/common.ts b/public/test/mocks/common.ts
index 1531f2ed176..64d12fdf725 100644
--- a/public/test/mocks/common.ts
+++ b/public/test/mocks/common.ts
@@ -7,10 +7,10 @@ export const backendSrv = {
 };
 
 export function createNavTree(...args) {
-  let root = [];
+  const root = [];
   let node = root;
-  for (let arg of args) {
-    let child = { id: arg, url: `/url/${arg}`, text: `${arg}-Text`, children: [] };
+  for (const arg of args) {
+    const child = { id: arg, url: `/url/${arg}`, text: `${arg}-Text`, children: [] };
     node.push(child);
     node = child.children;
   }