javascript - How does google analytics collect its data?

Question

Yes, I know you have to embed the google analytics javascript into your page.

But how is the collected information submitted to the google analytics server?

For example an AJAX request will not be possible because of the browsers security settings (cross domain scripting).

Maybe someone had already a look at the confusing google javascript code?

Answer 1

When html page makes a request for a ga.js file the http protocol sends big amount of data, about IP, refer, browers, language, system. There is no need to use ajax.

But still some data cant be achieved this way, so GA script puts image into html with additional parameters, take a look at this example:

http://www.google-analytics.com/__utm.gif?utmwv=4.3&utmn=1464271798&utmhn=www.example.com&utmcs=UTF-8&utmsr=1920x1200&utmsc=32-bit&utmul=en-us&utmje=1&utmfl=10.0%20r22&utmdt=Page title&utmhid=1805038256&utmr=0&utmp=/&utmac=cookie value

This is a blank image, sometimes called a tracking pixel, that GA puts into HTML.