ABalytics.js: Client-side A/B Testing With Google Analytics

You can't reliably use Array#concat on the _gaq object. Once Google Analytics loads, it replaces the _gaq array with a custom object that has it's own push() method. That object doesn't have concat() on it.

So, your core coding style will only work with very particular GA implementations; anything that deviates from that could very easily break or be subject to race conditions.

You'll also get better results if you use events rather than custom variables; custom variable reporting isn't as flexible and can be very confusing (ie, visit start). It'll also mitigate the need to use concat() to cut the line, since Events can be fired at any time (whereas custom variables need to happen before the first hit of the session to be well-reported).

I also really like the idea, though. I actually pass all my Optimizely test results as Google Analytics events with this snippet:

     if (window.optimmizely && optimizely.variationNamesMap) {
		var optmap = optimizely.variationNamesMap;
		for (var expt in optmap) {
			if (optmap.hasOwnProperty(expt)) {
				_gaq.push(["_trackEvent", "Optimizely", optimizely.allExperiments[expt].name, optmap[expt], 0, true]);
			}
		}
	}

Checking out the source code, this isn't going to work in IE8 and earlier without some small tweaks. IE didn't support `document.getElementsByClassName(string)` until IE9. It would be a small rewrite to make it work with IDs instead of classes (or you could use a shim).

[EDIT]: . . . But I like the idea. Might even use it next time I'm working with GA.

My first thought upon seeing this was, "Where are the statistics so that you know if you are just ahead by chance?"

My second thought was, "Testing is so much better than not testing, this is still worthwhile."

Seriously, if you aren't testing, do it. If you are, this is something to graduate out of.

Great job. I came up with my own ghetto solution using event tracking, yours is definitely better.

Very Nice! Personally, I would have loved a code example inside the post.

Thanks for going MIT.

Just me, or does anyone else miss Multivariate testing? It's impossible for me to use A/B testing with shopping cart software when it loads dynamic content (like the cart or checkout processes). Unless I'm doing it wrong?

looks nice and this is just an initial thought, it looks like the holding content in the HTML is replaced by either case A or B from the script, will it run with the holding text being case A and swapping out only when B is picked by the script therefore avoiding a possible content flicker some of the time? of course this may not be desirable on larger content.