Hosting your own analytics.js

When reducing your HTTP requests for front-end optimization reasons, one will eventually stumble upon the Google Analytics (GA) snippet. The GA snippet triggers an asynchronous request to download the analytics.js file from Google servers from the moment the snippet is processed on your page. Because it is asynchronous (in the browsers that support this behavior) it won’t block further script loading/execution and DOM rendering much, but it is still an extra HTTP request, DNS lookup, dependence on a server you do not control, etc. So for the situations you might want to host the analytics.js script yourself and/or combine it with your other scripts, let’s document how to do so.

Note that this is not encouraged (by Google) because loading it remotely ensures it will always be the latest version including the newest features.

Here’s the current (it has changed way too often) snippet that GA gives you:

(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
	(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
	m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-########-#', 'auto');
ga('send', 'pageview');

When unminifying it, it becomes easier to understand:


(function(){


	window['GoogleAnalyticsObject'] = 'ga';
	window['ga'] = window['ga'] || function(){
		window['ga'].q = window['ga'].q || [];
		window['ga'].q.push(arguments);
	},
	window['ga'].l = 1 * new Date();


	var a = document.createElement('script');
	var m = document.getElementsByTagName('script')[0];
	a.async = 1;
	a.src = '//www.google-analytics.com/analytics.js';
	m.parentNode.insertBefore(a, m);

})();


ga('create', 'UA-########-#', 'auto');
ga('send', 'pageview');

So… the snippet adds an object window.ga which is by itself callable as a function, but also contains the array “q” and the variable “l”. Q being an array of actions to perform (a queue), and L being a timestamp. It then inserts a script tag to load the external script, which whenever it is loaded – this is unpredictable since it is asynchronous – will process the values from the global variables. When ga() is called later on, it adds whatever arguments it is given as an array to the “q” array inside itself.

1. Download analytics.js

Let’s start by pulling in the script from

2. Include it in your build process

Concatinate it along with your other scripts, following your project’s methods. It can be included before or after the initialization snippet. Both will work.

3. Initiate it

In our case we take the original snippet, leave out the dynamic script loading and wrapping it inside an anonymous function is not necessary since we’ll only set global variables. Also the window['GoogleAnalyticsObject'] = 'ga' can be left out because ‘ga’ is the default fallback for when you don’t set this variable.


window.ga = window.ga || function(){
	window.ga.q = window.ga.q || [];
	window.ga.q.push(arguments);
};
ga.l = 1 * new Date();


ga('create', 'UA-########-#', 'auto');
ga('send', 'pageview');

Or shorter if you’re already in the global scope:

var ga = ga || function(){
	ga.q = ga.q || [];
	ga.q.push(arguments);
};
ga.l = 1 * new Date();
ga('create', 'UA-########-#', 'auto');
ga('send', 'pageview');

Even shorter if you are including analytics.js before initializing it. In that case window.ga is sure to be accessible and won’t need to be (re)defined:

ga('create', 'UA-########-#', 'auto');
ga('send', 'pageview');

That’s it. GA will now act just as if it was loaded via the snippet.
Do try to keep the local analytics.js up to date. Manually or ideally via a build process.

Something to avoid

Technically you can define window.ga with its initial values in a shorter fashion like so:

window.ga = {
	q: [
		['create', 'UA-########-#', 'auto'],
		['send', 'pageview']
	],
	l: Date.now()
};

But then you lose the functionality of interacting with GA later on (custom event tracking), because it won’t act as a callable function anymore.

Posted by Berend on August 23, 2014