Google analytics

<script async="" src="//www.google-analytics.com/analytics.js"></script>

<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');

  var GA_LOCAL_STORAGE_KEY = 'ga:clientId';
  if (window.localStorage) {
    ga('create', 'UA-366077-13', {
      'storage': 'none',
      'clientId': localStorage.getItem(GA_LOCAL_STORAGE_KEY)
    });
    ga(function(tracker) {
      localStorage.setItem(GA_LOCAL_STORAGE_KEY, tracker.get('clientId'));
    });
    ga('send', 'pageview', '/[fiddle]/[revision]/'); // where `url_structure` is for example `/[user]/[fiddle]/[revision]/embedded/js,css/`
  }
</script>