Add AJAX Request to Google Analytics

If you use jQuery you can bind to the global AjaxComplete event to fire a Pageview everytime an Ajax call completes:

jQuery(document).ajaxComplete(function(e, xhr, settings){
  var d = document.location.pathname + document.location.search + document.location.hash;
  _gaq.push(['_trackPageview', d]);
});

Source: http://stackoverflow.com/questions/7737549/google-analytics-and-loading-a-page-using-ajax-get-request

JSON Response in Symfony

If you want an action returns with json data, create something like this:

public function executeJson(sfWebRequest $request)
{
   $this->getResponse()->setContentType('application/json');
   // create the data
   $data = "something";
   return $this->renderText(json_encode($data));
}