GA external link tracker

track_external_links.js

// Place this code just before the closing body tag: </body>
(function() { try {
  var host = location.href.match(/^https?:\/\/([^\/]+)/i)[1];
  
  // Find all links in current document
  var links = document.getElementsByTagName('a');
  
  // Register click handlers to external links
  for(var i = 0; i < links.length; i++) {
    var href = links[i].href;
    var isExternal =
      !href.match(/^javascript\:/i) &&
      href.replace(/^https?:\/\//i, '').indexOf(host) !== 0 &&
      href.match(/^https?:\/\//i);
    if(isExternal) {
      if(links[i].addEventListener) {
        links[i].addEventListener('click', clickHandler);
      } else {
        links[i].attachEvent('onclick', clickHandler);
      }
    }
  }

  function clickHandler(e) {
    var source = e.srcElement || e.target;
    var href = source.href;
    var newWindow =
      (source.target && !source.target.match(/^_(self|parent|top)$/i)) ||
      e.which > 1 || e.shiftKey || e.altKey || e.metaKey || e.ctrlKey;

    if(newWindow) {
      // For the link opens in new window, call GA without hit callback.
      ga('send', 'event', {
        eventCategory: 'outbound',
        eventAction: 'click',
        eventLabel: href
      });
      return true;
    } else {
      // For the link opens in current window, prevent click event and use hit callback.
      ga('send', 'event', {
        eventCategory: 'outbound',
        eventAction: 'click',
        eventLabel: href,
        hitCallback: function() {location.href = href;}
      });
      e.preventDefault && e.preventDefault();
      return false;
    }
  }
} catch(e) {} })();