Pre-fetch editor script

[MAILPOET-2376]

assets/js/src/newsletters/types.jsx

@@ -173,6 +173,7 @@ class NewsletterTypes extends React.Component {
 
     return (
       <div>
+        <link rel="prefetch" href={window.mailpoet_editor_javascript_url} as="script" />
         <h1>{MailPoet.I18n.t('pickCampaignType')}</h1>
 
         <Breadcrumb step="type" />

lib/Twig/Assets.php

@@ -25,6 +25,11 @@ class Assets extends AbstractExtension {
         [$this, 'generateJavascript'],
         ['is_safe' => ['all']]
       ),
+      new TwigFunction(
+        'getJavascriptScriptUrl',
+        [$this, 'getJavascriptScriptUrl'],
+        ['is_safe' => ['all']]
+      ),
       new TwigFunction(
         'image_url',
         [$this, 'generateImageUrl'],
@@ -59,16 +64,23 @@ class Assets extends AbstractExtension {
 
     foreach ($scripts as $script) {
       $output[] = sprintf(
-        '<script type="text/javascript" src="%s/%s/%s"></script>',
-        $this->_globals['assets_url'],
-        strpos($script, 'lib/') === 0 ? 'js' : 'dist/js',
-        $this->getAssetFileName($this->_globals['assets_manifest_js'], $script)
+        '<script type="text/javascript" src="%s"></script>',
+        $this->getJavascriptScriptUrl($script)
       );
     }
 
     return join("\n", $output);
   }
 
+  function getJavascriptScriptUrl($script) {
+    return sprintf(
+      '%s/%s/%s',
+      $this->_globals['assets_url'],
+      strpos($script, 'lib/') === 0 ? 'js' : 'dist/js',
+      $this->getAssetFileName($this->_globals['assets_manifest_js'], $script)
+    );
+  }
+
   function generateImageUrl($path) {
     return $this->appendVersionToUrl(
       $this->_globals['assets_url'] . '/img/' . $path

views/newsletters.html

@@ -45,6 +45,7 @@
       var mailpoet_mss_active = <%= json_encode(mss_active) %>;
       var mailpoet_free_plan_announcement_seen = !!+'<%= settings.free_plan_announcement_seen %>';
       var mailpoet_mta_method = '<%= settings.mta.method %>';
+      var mailpoet_editor_javascript_url = '<%= getJavascriptScriptUrl("newsletter_editor.js") %>';
       var mailpoet_subscribers_count = <%= subscribers_count %>;
 
       <% if not(premium_plugin_active) %>