Software I like: Chrome Coverage Tab

October 7, 2021

While both Chrome and Firefox have great developer tools; I had almost forgotten that Chrome has a Coverage Tab ~ I hadn’t needed it in a long time.

coverage tab screenshot

It does both JavaScript and CSS; although I’ve only used the CSS part. For JavaScript, it is often easier to instrument procedural code with console.log.

How to Use it?

I think the instructions in the documentation (same link as above) are pretty good.

My Experience

I recently inherited an application that someone else wrote. If CSS is hard to understand, someone else’s CSS can be a real challenge. This tweet felt especially relevant:

css is hell

With the coverage tab, you get an idea of what’s used and what isn’t:

One thing to keep in mind: the coverage tab is dynamic … something highlighted in red might turn green when you navigate to different part of the page – or when you activate it; either through hover, or some JavaScript action.

The coverage tab is more of a “guide” than a guarantee… Something green is definitely in use; while something red is not currently used.

Where is it?

It’s not easily discoverable – If you don’t know it’s there, it’s almost hopeless… (shame 😢)

Open Developer Tools and follow the clicks:

finding the coverage tab in chrome

(sidenote: whoah… there’s a lot more tools here than I expected)

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