Javascript performance analytics

Question

I want to make my web applications faster.

For now I profile my web applications on a few test machines, and test some parts on jsPerf. However this only gives me limited insight about how the applications run when used by my clients.

What I would want is to measure performance "in the wild", when the scripts are in production.

I understand it will occur an overhead. However by only profiling specific parts of the code for each user, then combining those reports, it should be possible to get a complete picture with next to no performance hit.

Are there already solutions like this? Does Google Analytics or Google Webmaster Tools provide anything like this? I can't find any such thing.

Answer 1

There is no proper JS profiling in Google Analytics. You can use user timings to test how long your scripts run or how it takes to load them. And if you use Google Tag Manager you can implement the Javascript error listener that tracks unhandled javascript exceptions (i.e. it gives the error message and the offending script and the line in which the error happened).

This provides at least some insight into how your javascript behaves in the wild, but (IMO) it's not actually "profiling".