A simple javascript file that attaches to jquerys ajax events and logs metrics based on server performance.

analytics.js

(function() {

	$(document).ready(function() {

		function saveTime(e, jqxhr, settings) {
			settings.startTime = new Date().getTime();
		}

		function registerTime(e, jqxhr, settings) {
			_gaq.push(['_trackEvent', 'AjaxResponseTime', settings.type,  settings.url.split('?')[0] ,(new Date().getTime() - settings.startTime), true]);
		}

		$(document).ajaxSend(saveTime);
		$(document).ajaxComplete(registerTime);

		$(document).ajaxError(function(event, xhr, settings) {
			_gaq.push(['_trackEvent', 'AjaxError', xhr.status || xhr.statusText || 'Unknown', settings.url.split('?')[0],(new Date().getTime() - settings.startTime), true]);
		});


		window.onerror = function(msg, url, lineno) {
			_gaq.push(['_trackEvent', 'JavaScriptError', msg, url+":"+lineno, true]);
		};

	});
})();