Set up a Custom Dimension in Google Analytics

custom-dimension-google-analytics.js

<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','https://www.google-analytics.com/analytics.js','ga');

// Creates an adblock detection plugin.
ga('provide', 'adblockTracker', function(tracker, opts) {
  var ad = document.createElement('ins');
  ad.className = 'AdSense';
  ad.style.display = 'block';
  ad.style.position = 'absolute';
  ad.style.top = '-1px';
  ad.style.height = '1px';
  document.body.appendChild(ad);
  tracker.set('dimension' + opts.dimensionIndex, !ad.clientHeight);
  document.body.removeChild(ad);
});

// TODO: Replace UA-XXXXX-Y with you tracking ID.
ga('create', 'UA-XXXXX-Y', 'auto');
ga('require', 'adblockTracker', {dimensionIndex: 1});
ga('send', 'pageview');
</script>