diff --git a/core/misc/ajax.es6.js b/core/misc/ajax.es6.js
index 4cb008ff03..6bded620ca 100644
--- a/core/misc/ajax.es6.js
+++ b/core/misc/ajax.es6.js
@@ -1011,16 +1011,16 @@
      *   A optional jQuery selector string.
      * @param {object} [response.settings]
      *   An optional array of settings that will be used.
-     * @param {number} [status]
-     *   The XMLHttpRequest status.
      */
-    insert: function (ajax, response, status) {
+    insert: function (ajax, response) {
       // Get information from the response. If it is not there, default to
       // our presets.
-      var $wrapper = response.selector ? $(response.selector) : $(ajax.wrapper);
-      var method = response.method || ajax.method;
-      var effect = ajax.getEffect(response);
-      var settings;
+      const $wrapper = response.selector ? $(response.selector) : $(ajax.wrapper);
+      const method = response.method || ajax.method;
+      const effect = ajax.getEffect(response);
+
+      // Apply any settings from the returned JSON if available.
+      const settings = response.settings || ajax.settings || drupalSettings;
 
       // We don't know what response.data contains: it might be a string of text
       // without HTML, so don't rely on jQuery correctly interpreting
@@ -1031,35 +1031,35 @@
       // context object that includes top-level text nodes. Therefore text nodes
       // will be wrapped with a <span> element. This also gives themers the
       // possibility to style the response.
-      var $newContent;
+      let $newContent;
       // We use the trimmed data to be able to detect cases when the response
       // has only top-level elements or comment nodes with extra whitespace
       // around. In that case whitespaces are removed and the response
       // should not be wrapped.
-      // For exemple:
+      // For example:
       //   '  <div>content</div> ' is equivalent to '<div>content</div>' and
       // no extra wrapper will be added.
-      var trimedData = response.data.trim();
+      const trimmedData = response.data.trim();
       // List of DOM nodes contained in the response for processing.
-      var responseDataNodes;
+      let responseDataNodes;
 
       // When 'data' is empty or is only whitespace, manually create the node
       // array because parseHTML would return null.
-      if (trimedData === '') {
+      if (trimmedData === '') {
         responseDataNodes = [document.createTextNode(response.data)];
       }
       else {
-        responseDataNodes = $.parseHTML(trimedData, true);
+        responseDataNodes = $.parseHTML(trimmedData, true);
       }
       // Check every node for it's type to decide if wrapping is necessary.
-      var onlyElementNodes = responseDataNodes.every(function (element) {
+      const onlyElementNodes = responseDataNodes.every(function (element) {
         return element.nodeType === Node.ELEMENT_NODE || element.nodeType === Node.COMMENT_NODE;
       });
 
-      // When there are only element and/or comment nodes in the reponse, no
+      // When there are only element and/or comment nodes in the response, no
       // extra wrapping necessary.
       if (onlyElementNodes) {
-        $newContent = $(trimedData);
+        $newContent = $(trimmedData);
       }
       // When there are other types of top-level nodes, the response need to be
       // wrapped.
@@ -1072,7 +1072,7 @@
         else {
           $newContent = $('<div></div>');
         }
-        // Use reponse.data to keep whitespace as-is.
+        // Use response.data to keep whitespace as-is.
         $newContent.html(response.data);
       }
 
@@ -1083,7 +1083,6 @@
         case 'replaceAll':
         case 'empty':
         case 'remove':
-          settings = response.settings || ajax.settings || drupalSettings;
           Drupal.detachBehaviors($wrapper.get(0), settings);
       }
 
@@ -1097,10 +1096,11 @@
 
       // Determine which effect to use and what content will receive the
       // effect, then show the new content.
-      if ($newContent.find('.ajax-new-content').length > 0) {
-        $newContent.find('.ajax-new-content').hide();
+      const $ajaxNewContent = $newContent.find('.ajax-new-content');
+      if ($ajaxNewContent.length) {
+        $ajaxNewContent.hide();
         $newContent.show();
-        $newContent.find('.ajax-new-content')[effect.showEffect](effect.showSpeed);
+        $ajaxNewContent[effect.showEffect](effect.showSpeed);
       }
       else if (effect.showEffect !== 'show') {
         $newContent[effect.showEffect](effect.showSpeed);
@@ -1109,9 +1109,7 @@
       // Attach all JavaScript behaviors to the new content, if it was
       // successfully added to the page, this if statement allows
       // `#ajax['wrapper']` to be optional.
-      if ($newContent.parents('html').length > 0) {
-        // Apply any settings from the returned JSON if available.
-        settings = response.settings || ajax.settings || drupalSettings;
+      if ($newContent.parents('html').length) {
         // Attach behaviors to all element nodes.
         $newContent.each(function () {
           if (this.nodeType === Node.ELEMENT_NODE) {
diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 5f4b69f7e6..2177c7bc71 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -472,22 +472,23 @@
 
   Drupal.AjaxCommands = function () {};
   Drupal.AjaxCommands.prototype = {
-    insert: function insert(ajax, response, status) {
+    insert: function insert(ajax, response) {
       var $wrapper = response.selector ? $(response.selector) : $(ajax.wrapper);
       var method = response.method || ajax.method;
       var effect = ajax.getEffect(response);
-      var settings;
 
-      var $newContent;
+      var settings = response.settings || ajax.settings || drupalSettings;
+
+      var $newContent = void 0;
 
-      var trimedData = response.data.trim();
+      var trimmedData = response.data.trim();
 
-      var responseDataNodes;
+      var responseDataNodes = void 0;
 
-      if (trimedData === '') {
+      if (trimmedData === '') {
         responseDataNodes = [document.createTextNode(response.data)];
       } else {
-        responseDataNodes = $.parseHTML(trimedData, true);
+        responseDataNodes = $.parseHTML(trimmedData, true);
       }
 
       var onlyElementNodes = responseDataNodes.every(function (element) {
@@ -495,7 +496,7 @@
       });
 
       if (onlyElementNodes) {
-        $newContent = $(trimedData);
+        $newContent = $(trimmedData);
       } else {
           if (responseDataNodes.length === 1 || $wrapper.css('display') !== 'block') {
             $newContent = $('<span></span>');
@@ -512,7 +513,6 @@
         case 'replaceAll':
         case 'empty':
         case 'remove':
-          settings = response.settings || ajax.settings || drupalSettings;
           Drupal.detachBehaviors($wrapper.get(0), settings);
       }
 
@@ -522,17 +522,16 @@
         $newContent.hide();
       }
 
-      if ($newContent.find('.ajax-new-content').length > 0) {
-        $newContent.find('.ajax-new-content').hide();
+      var $ajaxNewContent = $newContent.find('.ajax-new-content');
+      if ($ajaxNewContent.length) {
+        $ajaxNewContent.hide();
         $newContent.show();
-        $newContent.find('.ajax-new-content')[effect.showEffect](effect.showSpeed);
+        $ajaxNewContent[effect.showEffect](effect.showSpeed);
       } else if (effect.showEffect !== 'show') {
         $newContent[effect.showEffect](effect.showSpeed);
       }
 
-      if ($newContent.parents('html').length > 0) {
-        settings = response.settings || ajax.settings || drupalSettings;
-
+      if ($newContent.parents('html').length) {
         $newContent.each(function () {
           if (this.nodeType === Node.ELEMENT_NODE) {
             Drupal.attachBehaviors(this, settings);
diff --git a/core/modules/system/tests/modules/ajax_test/js/insert-ajax.es6.js b/core/modules/system/tests/modules/ajax_test/js/insert-ajax.es6.js
index 4c5bb61749..94da75c135 100644
--- a/core/modules/system/tests/modules/ajax_test/js/insert-ajax.es6.js
+++ b/core/modules/system/tests/modules/ajax_test/js/insert-ajax.es6.js
@@ -8,30 +8,30 @@
   'use strict';
 
   Drupal.behaviors.insertTest = {
-    attach: function (context, settings) {
+    attach: function (context) {
       $('.ajax-insert').once('ajax-insert').on('click', function (event) {
         event.preventDefault();
-        var ajaxSettings = {
+        const ajaxSettings = {
           url: event.currentTarget.getAttribute('href'),
           wrapper: 'ajax-target',
           base: false,
           element: false,
           method: event.currentTarget.getAttribute('data-method')
         };
-        var myAjaxObject = Drupal.ajax(ajaxSettings);
+        const myAjaxObject = Drupal.ajax(ajaxSettings);
         myAjaxObject.execute();
       });
 
       $('.ajax-insert-inline').once('ajax-insert').on('click', function (event) {
         event.preventDefault();
-        var ajaxSettings = {
+        const ajaxSettings = {
           url: event.currentTarget.getAttribute('href'),
           wrapper: 'ajax-target-inline',
           base: false,
           element: false,
           method: event.currentTarget.getAttribute('data-method')
         };
-        var myAjaxObject = Drupal.ajax(ajaxSettings);
+        const myAjaxObject = Drupal.ajax(ajaxSettings);
         myAjaxObject.execute();
       });
 
diff --git a/core/modules/system/tests/modules/ajax_test/js/insert-ajax.js b/core/modules/system/tests/modules/ajax_test/js/insert-ajax.js
index 9bc9b8be0a..4f8dba29ab 100644
--- a/core/modules/system/tests/modules/ajax_test/js/insert-ajax.js
+++ b/core/modules/system/tests/modules/ajax_test/js/insert-ajax.js
@@ -1,8 +1,7 @@
 /**
 * DO NOT EDIT THIS FILE.
-* All changes should be applied to ./modules/system/tests/modules/ajax_test/js/insert-ajax.es6.js
 * See the following change record for more information,
-* https://www.drupal.org/node/2873849
+* https://www.drupal.org/node/2815083
 * @preserve
 **/
 
@@ -10,7 +9,7 @@
   'use strict';
 
   Drupal.behaviors.insertTest = {
-    attach: function attach(context, settings) {
+    attach: function attach(context) {
       $('.ajax-insert').once('ajax-insert').on('click', function (event) {
         event.preventDefault();
         var ajaxSettings = {
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/Ajax/AjaxFormPageCacheTest.php b/core/tests/Drupal/FunctionalJavascriptTests/Ajax/AjaxFormPageCacheTest.php
index cf56c6241b..e3e9042b3a 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/Ajax/AjaxFormPageCacheTest.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/Ajax/AjaxFormPageCacheTest.php
@@ -67,8 +67,8 @@ public function testSimpleAJAXFormValue() {
     $session->getPage()->selectFieldOption('select', 'red');
 
     // Wait for the DOM to update.
-    $red_div = $this->assertSession()->waitForElement('css', "#ajax_selected_color span:contains('red')");
-    $this->assertNotNull($red_div, 'DOM update: The selected color DIV is red.');
+    $red_span = $this->assertSession()->waitForElement('css', "#ajax_selected_color span:contains('red')");
+    $this->assertNotNull($red_span, 'DOM update: The selected color SPAN is red.');
 
     // Confirm the operation of the UpdateBuildIdCommand.
     $build_id_second_ajax = $this->getFormBuildId();