Unit testing javascript for a memory leak

Question

Is there a way to unit test for javascript memory leaks? What I mean is, is there any way to access the heap directly from javascript code to check for detached DOM trees or increased memory usage?

I know you can do this from Chrome Dev Tools, but I'm wondering if there's a way to do it directly from my unit tests, since it seems tedious to write some code, take a heap snapshot, perform a potentially memory leaking operation, take another heap snapshot, and repeat for every single potentially memory leaking operation, every time a write another snippet of code. Not to mention that adding code in one place may cause an unexpected memory leak in another part of the application.

It's just that I wrote an application that had a huge memory leak, and I had to start from scratch. When I develop the application this time around, I want to make sure my unit tests can detect that I've just created a memory leak, and I can eliminate it as soon as possible.

I think I've seen tools like this for C++, but not for Javascript. Does anyone know of any? Thank you!

Answer 1

According to MDN's docs on window.performance, Google Chrome has a non-standard extension (window.performance.memory) that gives access to values like usedJSHeapSize, totalJSHeapSize, jsHeapSizeLimit.

To get byte-level precision, you need to use the --enable-precise-memory-info flag.

For Garbage Collection, the only way I've found to force a browser to perform GC is with Chromium, with a special command flag. When you run this command:

chromium-browser --js-flags='--expose_gc'

you get access to the method window.gc(), which you can call to force GC.

This may open the possibility for testing memory usage in unit tests, for example.

Answer 2

For Node.js there's leakage that can be used to perform memory related unit tests. If your test involves DOM, you may try using jsdom to simulate the browser behavior, but I cannot guarantee it will give you the same result.