Google Analytics ga.js keeps changing for each request - why?

Question

If you keep on refreshing https://ssl.google-analytics.com/ga.js you will notice that the contents keeps switching between two versions. One starting with:

function(){var s=true,t=false,aa=window,u=undefined,v=Math,ba="push",fa="slice",ga="cookie",y="charAt",z="indexOf",A="gaGlobal",ha="getTime",ja="toString",B="window",D="length

and the other

(function(){var aa="_gat",ba="_gaq",r=true,v=false,w=undefined,ca=document,da="4.7.2",y="length",z="cookie",A="location",ea="gaUserPrefs",fa="ioo",B="&",C="=",D="_utma=",

Update:

I can see that one file contains da="4.7.2" and the other one contains na="4.8.6". It looks like different versions numbers.

Does anyone know anything about this?

Is this normal?

Answer 1

I cannot reproduce this.
Check your proxy configuration; you may have a bad cache.

Answer 2

You're right. There was a change happening. Google was slowly releasing a new version (4.8.6), and you must have been caught at some sort of weird mid-release point.

From GA's Release Notes:

Release 2010-10 (October 4, 2010)

This release contains regular maintenance including bug fixes and refactorings. There is no change to the public APIs or functionality.

Because of the nature and size of Google's servers, this sort of change takes a long time to push out.

Ibid:

Note that you and your users may not see the updated ga.js right away because: Changes are incrementally rolled out over several days across Google's global data center infrastructure. Users of your website may temporarily have older versions of our javascript cached in their browsers.