like-button-async.html

<div id="fb-root"></div>
<script>(function(d, s, id) {
  var js, fjs = d.getElementsByTagName(s)[0];
  if (d.getElementById(id)) return;
  js = d.createElement(s); js.id = id;
  js.async = 1; /* Diese Zeile wurde hinzugefügt */
  js.src = "//connect.facebook.net/de_DE/sdk.js#xfbml=1&version=v2.30847";
  fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));</script>