Merge pull request #4000 from magento-performance/MC-15439

PERF MC-15439

Author: vzabaznov

app/code/Magento/Theme/Controller/Result/JsFooterPlugin.php

@@ -0,0 +1,38 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Theme\Controller\Result;
+
+/**
+ * Plugin for putting messages to cookies
+ */
+class JsFooterPlugin
+{
+    /**
+     * Put all javascript to footer before sending the response
+     *
+     * @param \Magento\Framework\App\Response\Http $subject
+     * @return void
+     */
+    public function beforeSendResponse(\Magento\Framework\App\Response\Http $subject)
+    {
+        $content = $subject->getContent();
+        $script = [];
+        if (strpos($content, '</body') !== false) {
+            $pattern = '#<script[^>]*+(?<!text/x-magento-template.)>.*?</script>#is';
+            $content = preg_replace_callback(
+                $pattern,
+                function ($matchPart) use (&$script) {
+                    $script[] = $matchPart[0];
+                    return '';
+                },
+                $content
+            );
+            $subject->setContent(
+                str_replace('</body', implode("\n", $script) . "\n</body", $content)
+            );
+        }
+    }
+}

app/code/Magento/Theme/etc/frontend/di.xml

@@ -26,4 +26,7 @@
     <type name="Magento\Framework\Controller\ResultInterface">
         <plugin name="result-messages" type="Magento\Theme\Controller\Result\MessagePlugin"/>
     </type>
+    <type name="Magento\Framework\App\Response\Http">
+        <plugin name="result-js-footer" type="Magento\Theme\Controller\Result\JsFooterPlugin"/>
+    </type>
 </config>