diff --git a/core/misc/states.es6.js b/core/misc/states.es6.js
index 310fa3f97a..bfa1767515 100644
--- a/core/misc/states.es6.js
+++ b/core/misc/states.es6.js
@@ -31,8 +31,6 @@
   Drupal.behaviors.states = {
     attach(context, settings) {
       const $states = $(context).find('[data-drupal-states]');
-      let config;
-      const il = $states.length;
       const createState = (i, state, config) => {
         new states.Dependent({
           element: $($states[i]),
@@ -40,8 +38,9 @@
           constraints: config[state],
         });
       };
+      const il = $states.length;
       for (let i = 0; i < il; i++) {
-        config = JSON.parse($states[i].getAttribute('data-drupal-states'));
+        const config = JSON.parse($states[i].getAttribute('data-drupal-states'));
         Object.keys(config).forEach((state) => {
           createState(i, state, config);
         });
@@ -122,18 +121,11 @@
      *   dependee's compliance status.
      */
     initializeDependee(selector, dependeeStates) {
-      let state;
-      const self = this;
-
-      function stateEventHandler(e) {
-        self.update(e.data.selector, e.data.state, e.value);
-      }
-
       // Cache for the states of this dependee.
       this.values[selector] = {};
 
       Object.keys(dependeeStates).forEach((i) => {
-        state = dependeeStates[i];
+        let state = dependeeStates[i];
         // Make sure we're not initializing this selector/state combination
         // twice.
         if ($.inArray(state, dependeeStates) === -1) {
@@ -146,7 +138,9 @@
         this.values[selector][state.name] = null;
 
         // Monitor state changes of the specified state for this dependee.
-        $(selector).on(`state:${state}`, { selector, state }, stateEventHandler);
+        $(selector).on(`state:${state}`, { selector, state }, (e) => {
+          this.update(e.data.selector, e.data.state, e.value);
+        });
 
         // Make sure the event we just bound ourselves to is actually fired.
         new states.Trigger({ selector, state });
diff --git a/core/misc/states.js b/core/misc/states.js
index 113b8a8b06..db579f1870 100644
--- a/core/misc/states.js
+++ b/core/misc/states.js
@@ -13,8 +13,6 @@
   Drupal.behaviors.states = {
     attach: function attach(context, settings) {
       var $states = $(context).find('[data-drupal-states]');
-      var config = void 0;
-      var il = $states.length;
       var createState = function createState(i, state, config) {
         new states.Dependent({
           element: $($states[i]),
@@ -22,9 +20,10 @@
           constraints: config[state]
         });
       };
+      var il = $states.length;
 
       var _loop = function _loop(i) {
-        config = JSON.parse($states[i].getAttribute('data-drupal-states'));
+        var config = JSON.parse($states[i].getAttribute('data-drupal-states'));
         Object.keys(config).forEach(function (state) {
           createState(i, state, config);
         });
@@ -67,17 +66,10 @@
     initializeDependee: function initializeDependee(selector, dependeeStates) {
       var _this2 = this;
 
-      var state = void 0;
-      var self = this;
-
-      function stateEventHandler(e) {
-        self.update(e.data.selector, e.data.state, e.value);
-      }
-
       this.values[selector] = {};
 
       Object.keys(dependeeStates).forEach(function (i) {
-        state = dependeeStates[i];
+        var state = dependeeStates[i];
 
         if ($.inArray(state, dependeeStates) === -1) {
           return;
@@ -87,7 +79,9 @@
 
         _this2.values[selector][state.name] = null;
 
-        $(selector).on('state:' + state, { selector: selector, state: state }, stateEventHandler);
+        $(selector).on('state:' + state, { selector: selector, state: state }, function (e) {
+          _this2.update(e.data.selector, e.data.state, e.value);
+        });
 
         new states.Trigger({ selector: selector, state: state });
       });
diff --git a/core/modules/color/color.es6.js b/core/modules/color/color.es6.js
index c9c7871aca..9c5863002a 100644
--- a/core/modules/color/color.es6.js
+++ b/core/modules/color/color.es6.js
@@ -14,9 +14,6 @@
    */
   Drupal.behaviors.color = {
     attach(context, settings) {
-      let i;
-      let j;
-      let colors;
       // This behavior attaches by ID, so is only valid once on a page.
       const form = $(context).find('#system-theme-settings .color-form').once('color');
       if (form.length === 0) {
@@ -53,7 +50,7 @@
         // Each gradient line should have a height (or width for horizontal
         // gradients) of 10px (because we divided the height/width by 10
         // above).
-        for (j = 0; j < (settings.gradients[i].direction === 'vertical' ? height[i] : width[i]); ++j) {
+        for (let j = 0; j < (settings.gradients[i].direction === 'vertical' ? height[i] : width[i]); ++j) {
           gradient.append('<div class="gradient-line"></div>');
         }
       });
@@ -64,7 +61,7 @@
         const colorScheme = this.options[this.selectedIndex].value;
         if (colorScheme !== '' && schemes[colorScheme]) {
           // Get colors of active scheme.
-          colors = schemes[colorScheme];
+          const colors = schemes[colorScheme];
           Object.keys(colors).forEach((fieldName) => {
             callback($(`#edit-palette-${fieldName}`), colors[fieldName], false, true);
           });
@@ -154,6 +151,8 @@
        */
       function callback(input, color, propagate, colorScheme) {
         let matched;
+        let i;
+        let j;
         // Set background/foreground colors.
         $(input).css({
           backgroundColor: color,
diff --git a/core/modules/color/color.js b/core/modules/color/color.js
index 23bf7b6eb4..9c6f139639 100644
--- a/core/modules/color/color.js
+++ b/core/modules/color/color.js
@@ -8,10 +8,6 @@
 (function ($, Drupal) {
   Drupal.behaviors.color = {
     attach: function attach(context, settings) {
-      var i = void 0;
-      var j = void 0;
-      var colors = void 0;
-
       var form = $(context).find('#system-theme-settings .color-form').once('color');
       if (form.length === 0) {
         return;
@@ -40,7 +36,7 @@
 
         width.push(parseInt(gradient.css('width'), 10) / 10);
 
-        for (j = 0; j < (settings.gradients[i].direction === 'vertical' ? height[i] : width[i]); ++j) {
+        for (var j = 0; j < (settings.gradients[i].direction === 'vertical' ? height[i] : width[i]); ++j) {
           gradient.append('<div class="gradient-line"></div>');
         }
       });
@@ -49,7 +45,7 @@
         var schemes = settings.color.schemes;
         var colorScheme = this.options[this.selectedIndex].value;
         if (colorScheme !== '' && schemes[colorScheme]) {
-          colors = schemes[colorScheme];
+          var colors = schemes[colorScheme];
           Object.keys(colors).forEach(function (fieldName) {
             callback($('#edit-palette-' + fieldName), colors[fieldName], false, true);
           });
@@ -95,6 +91,8 @@
 
       function callback(input, color, propagate, colorScheme) {
         var matched = void 0;
+        var i = void 0;
+        var j = void 0;
 
         $(input).css({
           backgroundColor: color,
diff --git a/core/modules/content_translation/content_translation.admin.es6.js b/core/modules/content_translation/content_translation.admin.es6.js
index 94a59c34a0..84aaf7716f 100644
--- a/core/modules/content_translation/content_translation.admin.es6.js
+++ b/core/modules/content_translation/content_translation.admin.es6.js
@@ -17,7 +17,6 @@
       const $context = $(context);
       const options = drupalSettings.contentTranslationDependentOptions;
       let $fields;
-      let dependent_columns;
 
       function fieldsChangeHandler($fields, dependent_columns) {
         return function (e) {
@@ -31,7 +30,7 @@
       if (options && options.dependent_selectors) {
         Object.keys(options.dependent_selectors).forEach((field) => {
           $fields = $context.find(`input[name^="${field}"]`);
-          dependent_columns = options.dependent_selectors[field];
+          const dependent_columns = options.dependent_selectors[field];
 
           $fields.on('change', fieldsChangeHandler($fields, dependent_columns));
           Drupal.behaviors.contentTranslationDependentOptions.check($fields, dependent_columns);
diff --git a/core/modules/content_translation/content_translation.admin.js b/core/modules/content_translation/content_translation.admin.js
index e3ba01b5ba..ddaf0d20d5 100644
--- a/core/modules/content_translation/content_translation.admin.js
+++ b/core/modules/content_translation/content_translation.admin.js
@@ -11,7 +11,6 @@
       var $context = $(context);
       var options = drupalSettings.contentTranslationDependentOptions;
       var $fields = void 0;
-      var dependent_columns = void 0;
 
       function fieldsChangeHandler($fields, dependent_columns) {
         return function (e) {
@@ -22,7 +21,7 @@
       if (options && options.dependent_selectors) {
         Object.keys(options.dependent_selectors).forEach(function (field) {
           $fields = $context.find('input[name^="' + field + '"]');
-          dependent_columns = options.dependent_selectors[field];
+          var dependent_columns = options.dependent_selectors[field];
 
           $fields.on('change', fieldsChangeHandler($fields, dependent_columns));
           Drupal.behaviors.contentTranslationDependentOptions.check($fields, dependent_columns);
diff --git a/core/modules/editor/js/editor.admin.es6.js b/core/modules/editor/js/editor.admin.es6.js
index 9eaff8164b..e6b6dfd404 100644
--- a/core/modules/editor/js/editor.admin.es6.js
+++ b/core/modules/editor/js/editor.admin.es6.js
@@ -567,15 +567,12 @@
       // If any filter's current status forbids the editor feature, return
       // false.
       Drupal.filterConfiguration.update();
-      const disallowedFeature = Object.keys(Drupal.filterConfiguration.statuses).some((filterID) => {
-        const filterStatus = Drupal.filterConfiguration.statuses[filterID];
-        return !filterStatusAllowsFeature(filterStatus, feature);
-      });
-      if (disallowedFeature) {
-        return false;
-      }
-
-      return true;
+      const disallowedFeature = Object.keys(Drupal.filterConfiguration.statuses)
+        .some((filterID) => {
+          const filterStatus = Drupal.filterConfiguration.statuses[filterID];
+          return !filterStatusAllowsFeature(filterStatus, feature);
+        });
+      return !disallowedFeature;
     },
   };
 
@@ -878,13 +875,18 @@
      * up-to-date.
      */
     update() {
-      Object.keys(Drupal.filterConfiguration.statuses).forEach((filterID) => {
+      const filterConfiguration = Drupal.filterConfiguration;
+      const filterStatuses = filterConfiguration.statuses;
+      Object.keys(filterStatuses).forEach((filterID) => {
+        const filterStatusId = filterStatuses[filterID];
+
         // Update status.
-        Drupal.filterConfiguration.statuses[filterID].active = $(`[name="filters[${filterID}][status]"]`).is(':checked');
+        filterStatusId.active = $(`[name="filters[${filterID}][status]"]`).is(':checked');
 
         // Update current rules.
-        if (Drupal.filterConfiguration.liveSettingParsers[filterID]) {
-          Drupal.filterConfiguration.statuses[filterID].rules = Drupal.filterConfiguration.liveSettingParsers[filterID].getRules();
+        const liveSettingParsersFilterID = filterConfiguration.liveSettingParsers[filterID];
+        if (liveSettingParsersFilterID) {
+          filterStatusId.rules = liveSettingParsersFilterID.getRules();
         }
       });
     },
diff --git a/core/modules/editor/js/editor.admin.js b/core/modules/editor/js/editor.admin.js
index cdb51cede9..83b9f624c0 100644
--- a/core/modules/editor/js/editor.admin.js
+++ b/core/modules/editor/js/editor.admin.js
@@ -260,11 +260,7 @@
         var filterStatus = Drupal.filterConfiguration.statuses[filterID];
         return !filterStatusAllowsFeature(filterStatus, feature);
       });
-      if (disallowedFeature) {
-        return false;
-      }
-
-      return true;
+      return !disallowedFeature;
     }
   };
 
@@ -330,11 +326,16 @@
     liveSettingParsers: {},
 
     update: function update() {
-      Object.keys(Drupal.filterConfiguration.statuses).forEach(function (filterID) {
-        Drupal.filterConfiguration.statuses[filterID].active = $('[name="filters[' + filterID + '][status]"]').is(':checked');
+      var filterConfiguration = Drupal.filterConfiguration;
+      var filterStatuses = filterConfiguration.statuses;
+      Object.keys(filterStatuses).forEach(function (filterID) {
+        var filterStatusId = filterStatuses[filterID];
+
+        filterStatusId.active = $('[name="filters[' + filterID + '][status]"]').is(':checked');
 
-        if (Drupal.filterConfiguration.liveSettingParsers[filterID]) {
-          Drupal.filterConfiguration.statuses[filterID].rules = Drupal.filterConfiguration.liveSettingParsers[filterID].getRules();
+        var liveSettingParsersFilterID = filterConfiguration.liveSettingParsers[filterID];
+        if (liveSettingParsersFilterID) {
+          filterStatusId.rules = liveSettingParsersFilterID.getRules();
         }
       });
     }
diff --git a/core/modules/field_ui/field_ui.es6.js b/core/modules/field_ui/field_ui.es6.js
index 3fa297e3b0..a4c320acb4 100644
--- a/core/modules/field_ui/field_ui.es6.js
+++ b/core/modules/field_ui/field_ui.es6.js
@@ -212,7 +212,6 @@
       // Separate keys and values.
       const rowNames = [];
       const ajaxElements = [];
-      let rowName;
       Object.keys(rows).forEach((rowName) => {
         rowNames.push(rowName);
         ajaxElements.push(rows[rowName]);
diff --git a/core/modules/field_ui/field_ui.js b/core/modules/field_ui/field_ui.js
index 88d2672f45..5994ebf2ed 100644
--- a/core/modules/field_ui/field_ui.js
+++ b/core/modules/field_ui/field_ui.js
@@ -120,7 +120,6 @@
     AJAXRefreshRows: function AJAXRefreshRows(rows) {
       var rowNames = [];
       var ajaxElements = [];
-      var rowName = void 0;
       Object.keys(rows).forEach(function (rowName) {
         rowNames.push(rowName);
         ajaxElements.push(rows[rowName]);
diff --git a/core/modules/filter/filter.filter_html.admin.es6.js b/core/modules/filter/filter.filter_html.admin.es6.js
index 277b373fd4..13c3e9342f 100644
--- a/core/modules/filter/filter.filter_html.admin.es6.js
+++ b/core/modules/filter/filter.filter_html.admin.es6.js
@@ -135,16 +135,16 @@
      *   A list of new allowed tags.
      */
     _calculateAutoAllowedTags(userAllowedTags, newFeatures) {
-      let featureName;
-      let feature;
-      let featureRule;
-      let filterRule;
-      let tag;
       const editorRequiredTags = {};
+
       // Map the newly added Text Editor features to Drupal.FilterHtmlRule
       // objects (to allow comparing userTags with autoTags).
       Object.keys(newFeatures).forEach((featureName) => {
-        feature = newFeatures[featureName];
+        const feature = newFeatures[featureName];
+        let featureRule;
+        let filterRule;
+        let tag;
+
         for (let f = 0; f < feature.length; f++) {
           featureRule = feature[f];
           for (let t = 0; t < featureRule.required.tags.length; t++) {
diff --git a/core/modules/filter/filter.filter_html.admin.js b/core/modules/filter/filter.filter_html.admin.js
index ca3347d0cf..f0f3c47f98 100644
--- a/core/modules/filter/filter.filter_html.admin.js
+++ b/core/modules/filter/filter.filter_html.admin.js
@@ -74,15 +74,14 @@
         }
     },
     _calculateAutoAllowedTags: function _calculateAutoAllowedTags(userAllowedTags, newFeatures) {
-      var featureName = void 0;
-      var feature = void 0;
-      var featureRule = void 0;
-      var filterRule = void 0;
-      var tag = void 0;
       var editorRequiredTags = {};
 
       Object.keys(newFeatures).forEach(function (featureName) {
-        feature = newFeatures[featureName];
+        var feature = newFeatures[featureName];
+        var featureRule = void 0;
+        var filterRule = void 0;
+        var tag = void 0;
+
         for (var f = 0; f < feature.length; f++) {
           featureRule = feature[f];
           for (var t = 0; t < featureRule.required.tags.length; t++) {