core/lib/Drupal/Core/Ajax/AddJsCommand.php         | 44 ++++++++++++++++++
 .../Core/Ajax/AjaxResponseAttachmentsProcessor.php |  6 ++-
 core/misc/ajax.js                                  | 53 +++++++++++++++++++++-
 core/misc/dialog/dialog.ajax.js                    |  3 ++
 4 files changed, 103 insertions(+), 3 deletions(-)

diff --git a/core/lib/Drupal/Core/Ajax/AddJsCommand.php b/core/lib/Drupal/Core/Ajax/AddJsCommand.php
new file mode 100644
index 0000000..f7c0a8a
--- /dev/null
+++ b/core/lib/Drupal/Core/Ajax/AddJsCommand.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace Drupal\Core\Ajax;
+
+/**
+ * An AJAX command for adding JS to the page via ajax.
+ *
+ * This command is implemented by Drupal.AjaxCommands.prototype.add_js()
+ * defined in misc/ajax.js.
+ *
+ * @see misc/ajax.js
+ *
+ * @ingroup ajax
+ */
+class AddJsCommand implements CommandInterface {
+
+  /**
+   * An array containing the attributes of the scripts to be added to the page.
+   *
+   * @var string[]
+   */
+  protected $styles;
+
+  /**
+   * Constructs an AddJsCommand.
+   *
+   * @param array $scripts
+   */
+  public function __construct($scripts) {
+    $this->styles = $scripts;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function render() {
+
+    return [
+      'command' => 'add_js',
+      'data' => $this->styles,
+    ];
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Ajax/AjaxResponseAttachmentsProcessor.php b/core/lib/Drupal/Core/Ajax/AjaxResponseAttachmentsProcessor.php
index 45aa45e..6cb9f3e 100644
--- a/core/lib/Drupal/Core/Ajax/AjaxResponseAttachmentsProcessor.php
+++ b/core/lib/Drupal/Core/Ajax/AjaxResponseAttachmentsProcessor.php
@@ -174,11 +174,13 @@ protected function buildAttachmentsCommands(AjaxResponse $response, Request $req
     }
     if ($js_assets_header) {
       $js_header_render_array = $this->jsCollectionRenderer->render($js_assets_header);
-      $resource_commands[] = new PrependCommand('head', $this->renderer->renderPlain($js_header_render_array));
+      $scripts_attributes = array_map(function ($render_array) { return $render_array['#attributes']; }, $js_header_render_array);
+      $resource_commands[] = new AddJsCommand($scripts_attributes);
     }
     if ($js_assets_footer) {
       $js_footer_render_array = $this->jsCollectionRenderer->render($js_assets_footer);
-      $resource_commands[] = new AppendCommand('body', $this->renderer->renderPlain($js_footer_render_array));
+      $scripts_attributes = array_map(function ($render_array) { return $render_array['#attributes']; }, $js_footer_render_array);
+      $resource_commands[] = new AddJsCommand($scripts_attributes);
     }
     foreach (array_reverse($resource_commands) as $resource_command) {
       $response->addCommand($resource_command, TRUE);
diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index fefe9f3..74d1502 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -860,6 +860,7 @@
     // focus set by the Ajax command.
     var focusChanged = false;
     for (var i in response) {
+      console.log('[ajax.js] command to execute: ' + response[i].command, this.commands[response[i].command] ? 'command exists, executing' : 'command does NOT exist, SKIPPING!');
       if (response.hasOwnProperty(i) && response[i].command && this.commands[response[i].command]) {
         this.commands[response[i].command](this, response[i], status);
         if (response[i].command === 'invoke' && response[i].method === 'focus') {
@@ -1019,6 +1020,7 @@
       // our presets.
       var $wrapper = response.selector ? $(response.selector) : $(ajax.wrapper);
       var method = response.method || ajax.method;
+      console.log(method);
       var effect = ajax.getEffect(response);
       var settings;
 
@@ -1338,7 +1340,56 @@
           document.styleSheets[0].addImport(match[1]);
         } while (match);
       }
-    }
+    },
+
+    add_js: function (ajax, response, status) {
+      var head = document.getElementsByTagName('head')[0];
+      window.loaded = {};
+      for (var i in response.data) {
+        if (!response.data.hasOwnProperty(i)) {
+          continue;
+        }
+
+        // Prepare to load script.
+        var script = document.createElement('script');
+        script.type = 'text/javascript';
+        script.setAttribute('data-ajax', true);
+        for (var attributeName in response.data[i]) {
+          if (response.data[i].hasOwnProperty(attributeName)) {
+            script.setAttribute(attributeName, response.data[i][attributeName]);
+          }
+        }
+
+        // Track loading of script.
+        var src = response.data[i].src;
+        window.loaded[src] = false;
+        (function(src) {
+          script.onload = function () {
+            return function () {
+              console.log(src + ' finished loading!');
+              delete window.loaded[src];
+            };
+          }();
+        })(response.data[i].src);
+
+        // Start loading script.
+        head.appendChild(script);
+      }
+
+      console.log(Object.keys(window.loaded));
+      console.log('started loading');
+
+      function allJsIsLoaded() {
+        console.log(Object.keys(window.loaded).length);
+        return Object.keys(window.loaded).length === 0;
+      }
+      var maxIterations = 10000;
+      var c = 0;
+      while (!allJsIsLoaded() && c < maxIterations) {
+        c++; // This is evil, I know. But this MUST be blocking because the caller (Drupal.Ajax.prototype.success) is blocking. We can make this non-blocking if we can make the caller non-blocking too.
+      }
+      console.log('finished loading');
+    },
   };
 
 })(jQuery, window, Drupal, drupalSettings);
diff --git a/core/misc/dialog/dialog.ajax.js b/core/misc/dialog/dialog.ajax.js
index 3f1b0c2..6b8f89d 100644
--- a/core/misc/dialog/dialog.ajax.js
+++ b/core/misc/dialog/dialog.ajax.js
@@ -5,6 +5,8 @@
 
 (function ($, Drupal) {
 
+  console.log('dialog.ajax.js loaded');
+
   'use strict';
 
   /**
@@ -111,6 +113,7 @@
    *   Returns false if there was no selector property in the response object.
    */
   Drupal.AjaxCommands.prototype.openDialog = function (ajax, response, status) {
+    console.log('openDialog() ajax command called');
     if (!response.selector) {
       return false;
     }