jQUERY延迟加载外部JS

var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");

$.getScript(gaJsHost + "google-analytics.com/ga.js",function(){

try {

var pageTracker = _gat._getTracker("UA-123456-16");

pageTracker._trackPageview();

} catch(err) {}

});