Question

In Google’s documentation it is said that an event can be tracked in the following way:

<a onclick="_gaq.push(['_trackEvent', 'category', 'action', 'opt_label', opt_value]);">click me</a> 

or older version:

<a onclick="pageTracker._trackEvent('category', 'action', 'opt_label', opt_value);">click me</a>

I was looking with Firebug to the request that are made when a click on a link and I see there aborted request:

http://www.google-analytics.com/__utm.gif?utmwv=4.7.2&utmn=907737223&....

This happens because browser unload all javascript when user navigates to a new page. How in this case event tracking is performed?

Edit:
Since one picture can be worth a thousand words…

When I click a link firebug shows me this sequence of requests (here are shown first four, after follows requests to fill page content)

Answer 1

The problem is that there isn’t enough time for the script to finish running before the user is taken to the next page. What you can do is create a wrapper function for your GA code and in the onclick, call the wrapper function and after the GA code is triggered in your wrapper function, set a time out and update location.href with the link’s url. Example:

<a href="somepage.html" onclick="wrapper_function(this,'category', 'action', 'opt_label', 'opt_value');return false;">click me</a>

<script type='text/javascript'>
function wrapper_function(that,category,action,opt_label,opt_value) {
  _gaq.push(['_trackEvent', category, action, opt_label, opt_value]);
  window.setTimeout("window.location.href='" + that.href + "'", 1000);
}
</script>

code will vary a bit based on your link but hopefully you get the idea – basically it waits a little bit before taking the user to the target url to give the script some time to execute.

Update:
This answer was posted several years ago and quite a lot has happened since then, yet I continue to get feedback (and upvotes) occasionally, so I thought I’d update this answer with new info. This answer is still doable but if you are using Universal Analytics then there is a hitCallback function available. The hitCallback function is also available to their traditional _gaq (ga.js) but it’s not officially documented.