diff --git a/core/.eslintrc.passing.json b/core/.eslintrc.passing.json
index db5f24e49d9c93c37121e0e1405fc87687bcd5d8..8489a7d061867c3cd313c284eaa3bad5bad26007 100644
--- a/core/.eslintrc.passing.json
+++ b/core/.eslintrc.passing.json
@@ -7,7 +7,6 @@
     "no-shadow": "off",
     "no-restricted-syntax": "off",
     "no-new": "off",
-    "no-multi-assign": "off",
     "no-continue": "off",
     "new-cap": "off",
     "max-len": "off",
diff --git a/core/misc/displace.es6.js b/core/misc/displace.es6.js
index 0424d80fa51724d14f4fce50931c7bd548b1cbc6..6ac09f4e6aae63778a7e40ef991f0d7fd4e21c4d 100644
--- a/core/misc/displace.es6.js
+++ b/core/misc/displace.es6.js
@@ -73,7 +73,8 @@
    * @fires event:drupalViewportOffsetChange
    */
   function displace(broadcast) {
-    offsets = Drupal.displace.offsets = calculateOffsets();
+    offsets = calculateOffsets();
+    Drupal.displace.offsets = offsets;
     if (typeof broadcast === 'undefined' || broadcast) {
       $(document).trigger('drupalViewportOffsetChange', offsets);
     }
diff --git a/core/misc/displace.js b/core/misc/displace.js
index 890548f92f334241d59f739eb512eb91c0da085f..777aee478d75a2a7e742bce579d575e183bf1b8c 100644
--- a/core/misc/displace.js
+++ b/core/misc/displace.js
@@ -25,7 +25,8 @@
   };
 
   function displace(broadcast) {
-    offsets = Drupal.displace.offsets = calculateOffsets();
+    offsets = calculateOffsets();
+    Drupal.displace.offsets = offsets;
     if (typeof broadcast === 'undefined' || broadcast) {
       $(document).trigger('drupalViewportOffsetChange', offsets);
     }
diff --git a/core/misc/states.es6.js b/core/misc/states.es6.js
index fbf8db7c98c9599e2ff112e63de79a0ab3dbe2df..ec7a4e7e3a844020bd4a85c43839f63c62863824 100644
--- a/core/misc/states.es6.js
+++ b/core/misc/states.es6.js
@@ -12,7 +12,7 @@
    *
    * @namespace Drupal.states
    */
-  const states = Drupal.states = {
+  const states = {
 
     /**
      * An array of functions that should be postponed.
@@ -20,6 +20,8 @@
     postponed: [],
   };
 
+  Drupal.states = states;
+
   /**
    * Attaches the states.
    *
@@ -508,7 +510,8 @@
     /**
      * Original unresolved name.
      */
-    this.pristine = this.name = state;
+    this.pristine = state;
+    this.name = state;
 
     // Normalize the state name.
     let process = true;
diff --git a/core/misc/states.js b/core/misc/states.js
index 61bbf46c612eb9470d9d7fdb89429d8d6c84ffd0..2b9d3b886a67dd3b4844888468d6c06ec877c584 100644
--- a/core/misc/states.js
+++ b/core/misc/states.js
@@ -6,10 +6,12 @@
 **/
 
 (function ($, Drupal) {
-  var states = Drupal.states = {
+  var states = {
     postponed: []
   };
 
+  Drupal.states = states;
+
   Drupal.behaviors.states = {
     attach: function attach(context, settings) {
       var $states = $(context).find('[data-drupal-states]');
@@ -259,7 +261,8 @@
   };
 
   states.State = function (state) {
-    this.pristine = this.name = state;
+    this.pristine = state;
+    this.name = state;
 
     var process = true;
     do {
diff --git a/core/misc/tabledrag.es6.js b/core/misc/tabledrag.es6.js
index ce621da43d08197e1a899f3680400fb500a6cc88..abbe193862b67ff603b2d9dd2a8d76d685cd79ff 100644
--- a/core/misc/tabledrag.es6.js
+++ b/core/misc/tabledrag.es6.js
@@ -1107,14 +1107,16 @@
     const de = document.documentElement;
     const b = document.body;
 
-    const windowHeight = this.windowHeight = window.innerHeight || (de.clientHeight && de.clientWidth !== 0 ? de.clientHeight : b.offsetHeight);
+    const windowHeight = window.innerHeight || (de.clientHeight && de.clientWidth !== 0 ? de.clientHeight : b.offsetHeight);
+    this.windowHeight = windowHeight;
     let scrollY;
     if (document.all) {
-      scrollY = this.scrollY = !de.scrollTop ? b.scrollTop : de.scrollTop;
+      scrollY = !de.scrollTop ? b.scrollTop : de.scrollTop;
     }
     else {
-      scrollY = this.scrollY = window.pageYOffset ? window.pageYOffset : window.scrollY;
+      scrollY = window.pageYOffset ? window.pageYOffset : window.scrollY;
     }
+    this.scrollY = scrollY;
     const trigger = this.scrollSettings.trigger;
     let delta = 0;
 
diff --git a/core/misc/tabledrag.js b/core/misc/tabledrag.js
index e828bfe7566439b8dfb8d9eed7b36842b3269eb8..859b87e013a26cdd43750a13919bc7e9f841f984 100644
--- a/core/misc/tabledrag.js
+++ b/core/misc/tabledrag.js
@@ -701,13 +701,15 @@
     var de = document.documentElement;
     var b = document.body;
 
-    var windowHeight = this.windowHeight = window.innerHeight || (de.clientHeight && de.clientWidth !== 0 ? de.clientHeight : b.offsetHeight);
+    var windowHeight = window.innerHeight || (de.clientHeight && de.clientWidth !== 0 ? de.clientHeight : b.offsetHeight);
+    this.windowHeight = windowHeight;
     var scrollY = void 0;
     if (document.all) {
-      scrollY = this.scrollY = !de.scrollTop ? b.scrollTop : de.scrollTop;
+      scrollY = !de.scrollTop ? b.scrollTop : de.scrollTop;
     } else {
-      scrollY = this.scrollY = window.pageYOffset ? window.pageYOffset : window.scrollY;
+      scrollY = window.pageYOffset ? window.pageYOffset : window.scrollY;
     }
+    this.scrollY = scrollY;
     var trigger = this.scrollSettings.trigger;
     var delta = 0;
 
diff --git a/core/modules/ckeditor/js/ckeditor.admin.es6.js b/core/modules/ckeditor/js/ckeditor.admin.es6.js
index 5a2828c43e6d0528e8bed02ade3240759eeed272..c875fd64a09ca6287b1c11aa3b4f5da6eaa8b8b2 100644
--- a/core/modules/ckeditor/js/ckeditor.admin.es6.js
+++ b/core/modules/ckeditor/js/ckeditor.admin.es6.js
@@ -34,7 +34,7 @@
         $configurationForm.append(drupalSettings.ckeditor.toolbarAdmin);
 
         // Create a configuration model.
-        const model = Drupal.ckeditor.models.Model = new Drupal.ckeditor.Model({
+        Drupal.ckeditor.models.Model = new Drupal.ckeditor.Model({
           $textarea,
           activeEditorConfig: JSON.parse($textarea.val()),
           hiddenEditorConfig: drupalSettings.ckeditor.hiddenCKEditorConfig,
@@ -42,7 +42,7 @@
 
         // Create the configuration Views.
         const viewDefaults = {
-          model,
+          model: Drupal.ckeditor.models.Model,
           el: $('.ckeditor-toolbar-configuration'),
         };
         Drupal.ckeditor.views = {
diff --git a/core/modules/ckeditor/js/ckeditor.admin.js b/core/modules/ckeditor/js/ckeditor.admin.js
index f51341d4ae76baa91da8051d6fa250f57c24b66b..c3b62ecbcb738213f89c0b81883c25bea604b8d3 100644
--- a/core/modules/ckeditor/js/ckeditor.admin.js
+++ b/core/modules/ckeditor/js/ckeditor.admin.js
@@ -16,14 +16,14 @@
 
         $configurationForm.append(drupalSettings.ckeditor.toolbarAdmin);
 
-        var model = Drupal.ckeditor.models.Model = new Drupal.ckeditor.Model({
+        Drupal.ckeditor.models.Model = new Drupal.ckeditor.Model({
           $textarea: $textarea,
           activeEditorConfig: JSON.parse($textarea.val()),
           hiddenEditorConfig: drupalSettings.ckeditor.hiddenCKEditorConfig
         });
 
         var viewDefaults = {
-          model: model,
+          model: Drupal.ckeditor.models.Model,
           el: $('.ckeditor-toolbar-configuration')
         };
         Drupal.ckeditor.views = {
diff --git a/core/modules/contextual/js/contextual.toolbar.es6.js b/core/modules/contextual/js/contextual.toolbar.es6.js
index 7d0ae120733094b0e1f67be887e939aa706cc576..9538288d6c17c4f86be771c0a9bc2777a8daa18a 100644
--- a/core/modules/contextual/js/contextual.toolbar.es6.js
+++ b/core/modules/contextual/js/contextual.toolbar.es6.js
@@ -22,7 +22,7 @@
     }
 
     const contextualToolbar = Drupal.contextualToolbar;
-    const model = contextualToolbar.model = new contextualToolbar.StateModel({
+    contextualToolbar.model = new contextualToolbar.StateModel({
       // Checks whether localStorage indicates we should start in edit mode
       // rather than view mode.
       // @see Drupal.contextualToolbar.VisualView.persist
@@ -33,7 +33,7 @@
 
     const viewOptions = {
       el: $('.toolbar .toolbar-bar .contextual-toolbar-tab'),
-      model,
+      model: contextualToolbar.model,
       strings,
     };
     new contextualToolbar.VisualView(viewOptions);
diff --git a/core/modules/contextual/js/contextual.toolbar.js b/core/modules/contextual/js/contextual.toolbar.js
index b565f21838bfc427320caef86a862898f4d261ef..3b026d7355554c89be4e7efde0f6f314da5070d9 100644
--- a/core/modules/contextual/js/contextual.toolbar.js
+++ b/core/modules/contextual/js/contextual.toolbar.js
@@ -18,7 +18,7 @@
     }
 
     var contextualToolbar = Drupal.contextualToolbar;
-    var model = contextualToolbar.model = new contextualToolbar.StateModel({
+    contextualToolbar.model = new contextualToolbar.StateModel({
       isViewing: localStorage.getItem('Drupal.contextualToolbar.isViewing') !== 'false'
     }, {
       contextualCollection: Drupal.contextual.collection
@@ -26,7 +26,7 @@
 
     var viewOptions = {
       el: $('.toolbar .toolbar-bar .contextual-toolbar-tab'),
-      model: model,
+      model: contextualToolbar.model,
       strings: strings
     };
     new contextualToolbar.VisualView(viewOptions);
diff --git a/core/modules/quickedit/js/editors/formEditor.es6.js b/core/modules/quickedit/js/editors/formEditor.es6.js
index 1950b47bba7c482ec1891db5216ec6abea40baa3..be658d37a95412580c8b6406d5331ede830accbf 100644
--- a/core/modules/quickedit/js/editors/formEditor.es6.js
+++ b/core/modules/quickedit/js/editors/formEditor.es6.js
@@ -95,10 +95,11 @@
       const id = `quickedit-form-for-${fieldModel.id.replace(/[\/\[\]]/g, '_')}`;
 
       // Render form container.
-      const $formContainer = this.$formContainer = $(Drupal.theme('quickeditFormContainer', {
+      const $formContainer = $(Drupal.theme('quickeditFormContainer', {
         id,
         loadingMsg: Drupal.t('Loading…'),
       }));
+      this.$formContainer = $formContainer;
       $formContainer
         .find('.quickedit-form')
         .addClass('quickedit-editable quickedit-highlighted quickedit-editing')
diff --git a/core/modules/quickedit/js/editors/formEditor.js b/core/modules/quickedit/js/editors/formEditor.js
index 6ff6990eaf723dfe3a91ebc347376b3be96d2e3f..c4d875047435f98ac2f4212e20521f4353ecd2b3 100644
--- a/core/modules/quickedit/js/editors/formEditor.js
+++ b/core/modules/quickedit/js/editors/formEditor.js
@@ -59,10 +59,11 @@
 
       var id = 'quickedit-form-for-' + fieldModel.id.replace(/[\/\[\]]/g, '_');
 
-      var $formContainer = this.$formContainer = $(Drupal.theme('quickeditFormContainer', {
+      var $formContainer = $(Drupal.theme('quickeditFormContainer', {
         id: id,
         loadingMsg: Drupal.t('Loading…')
       }));
+      this.$formContainer = $formContainer;
       $formContainer.find('.quickedit-form').addClass('quickedit-editable quickedit-highlighted quickedit-editing').attr('role', 'dialog');
 
       if (this.$el.css('display') === 'inline') {
diff --git a/core/modules/quickedit/js/editors/plainTextEditor.es6.js b/core/modules/quickedit/js/editors/plainTextEditor.es6.js
index bb4bb3c2bc0b54cc8edf03e578b48cd53b69438a..92e5a5dd0f9bb9795d22895412b11c354cba13f4 100644
--- a/core/modules/quickedit/js/editors/plainTextEditor.es6.js
+++ b/core/modules/quickedit/js/editors/plainTextEditor.es6.js
@@ -27,14 +27,9 @@
 
       // Store the original value of this field. Necessary for reverting
       // changes.
-      let $textElement;
       const $fieldItems = this.$el.find('.quickedit-field');
-      if ($fieldItems.length) {
-        $textElement = this.$textElement = $fieldItems.eq(0);
-      }
-      else {
-        $textElement = this.$textElement = this.$el;
-      }
+      const $textElement = $fieldItems.length ? $fieldItems.eq(0) : this.$el;
+      this.$textElement = $textElement;
       editorModel.set('originalValue', $.trim(this.$textElement.text()));
 
       // Sets the state to 'changed' whenever the value changes.
diff --git a/core/modules/quickedit/js/editors/plainTextEditor.js b/core/modules/quickedit/js/editors/plainTextEditor.js
index e6f5afdeac127850c5e45fe4c64c9a58f020f0a0..dde834b86900d79e45116802db79e694eaf11b1a 100644
--- a/core/modules/quickedit/js/editors/plainTextEditor.js
+++ b/core/modules/quickedit/js/editors/plainTextEditor.js
@@ -15,13 +15,9 @@
       var editorModel = this.model;
       var fieldModel = this.fieldModel;
 
-      var $textElement = void 0;
       var $fieldItems = this.$el.find('.quickedit-field');
-      if ($fieldItems.length) {
-        $textElement = this.$textElement = $fieldItems.eq(0);
-      } else {
-        $textElement = this.$textElement = this.$el;
-      }
+      var $textElement = $fieldItems.length ? $fieldItems.eq(0) : this.$el;
+      this.$textElement = $textElement;
       editorModel.set('originalValue', $.trim(this.$textElement.text()));
 
       var previousText = editorModel.get('originalValue');
diff --git a/core/modules/toolbar/js/toolbar.es6.js b/core/modules/toolbar/js/toolbar.es6.js
index 4fdf090fbedb47ef234b6e6f600da09bcc04d99b..f715fc7fc96eabdf2dd96d1d5e8b886b67829fed 100644
--- a/core/modules/toolbar/js/toolbar.es6.js
+++ b/core/modules/toolbar/js/toolbar.es6.js
@@ -46,18 +46,21 @@
       // Process the administrative toolbar.
       $(context).find('#toolbar-administration').once('toolbar').each(function () {
         // Establish the toolbar models and views.
-        const model = Drupal.toolbar.models.toolbarModel = new Drupal.toolbar.ToolbarModel({
+        const model = new Drupal.toolbar.ToolbarModel({
           locked: JSON.parse(localStorage.getItem('Drupal.toolbar.trayVerticalLocked')),
           activeTab: document.getElementById(JSON.parse(localStorage.getItem('Drupal.toolbar.activeTabID'))),
           height: $('#toolbar-administration').outerHeight(),
         });
 
+        Drupal.toolbar.models.toolbarModel = model;
+
         // Attach a listener to the configured media query breakpoints.
         // Executes it before Drupal.toolbar.views to avoid extra rendering.
         for (const label in options.breakpoints) {
           if (options.breakpoints.hasOwnProperty(label)) {
             const mq = options.breakpoints[label];
-            const mql = Drupal.toolbar.mql[label] = window.matchMedia(mq);
+            const mql = window.matchMedia(mq);
+            Drupal.toolbar.mql[label] = mql;
             // Curry the model and the label of the media query breakpoint to
             // the mediaQueryChangeHandler function.
             mql.addListener(Drupal.toolbar.mediaQueryChangeHandler.bind(null, model, label));
@@ -88,7 +91,8 @@
         model.trigger('change:activeTray', model, model.get('activeTray'));
 
         // Render collapsible menus.
-        const menuModel = Drupal.toolbar.models.menuModel = new Drupal.toolbar.MenuModel();
+        const menuModel = new Drupal.toolbar.MenuModel();
+        Drupal.toolbar.models.menuModel = menuModel;
         Drupal.toolbar.views.menuVisualView = new Drupal.toolbar.MenuVisualView({
           el: $(this).find('.toolbar-menu-administration').get(0),
           model: menuModel,
diff --git a/core/modules/toolbar/js/toolbar.js b/core/modules/toolbar/js/toolbar.js
index 4f4ff5943f998789780ea95e58cb019dd21c09b8..547bcd9bac7aaebee17c39d8893fe71f07925334 100644
--- a/core/modules/toolbar/js/toolbar.js
+++ b/core/modules/toolbar/js/toolbar.js
@@ -26,16 +26,19 @@
       }
 
       $(context).find('#toolbar-administration').once('toolbar').each(function () {
-        var model = Drupal.toolbar.models.toolbarModel = new Drupal.toolbar.ToolbarModel({
+        var model = new Drupal.toolbar.ToolbarModel({
           locked: JSON.parse(localStorage.getItem('Drupal.toolbar.trayVerticalLocked')),
           activeTab: document.getElementById(JSON.parse(localStorage.getItem('Drupal.toolbar.activeTabID'))),
           height: $('#toolbar-administration').outerHeight()
         });
 
+        Drupal.toolbar.models.toolbarModel = model;
+
         for (var label in options.breakpoints) {
           if (options.breakpoints.hasOwnProperty(label)) {
             var mq = options.breakpoints[label];
-            var mql = Drupal.toolbar.mql[label] = window.matchMedia(mq);
+            var mql = window.matchMedia(mq);
+            Drupal.toolbar.mql[label] = mql;
 
             mql.addListener(Drupal.toolbar.mediaQueryChangeHandler.bind(null, model, label));
 
@@ -61,7 +64,8 @@
         model.trigger('change:isFixed', model, model.get('isFixed'));
         model.trigger('change:activeTray', model, model.get('activeTray'));
 
-        var menuModel = Drupal.toolbar.models.menuModel = new Drupal.toolbar.MenuModel();
+        var menuModel = new Drupal.toolbar.MenuModel();
+        Drupal.toolbar.models.menuModel = menuModel;
         Drupal.toolbar.views.menuVisualView = new Drupal.toolbar.MenuVisualView({
           el: $(this).find('.toolbar-menu-administration').get(0),
           model: menuModel,