Inspecting Animations in DevTools

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I stumbled upon the Animation panel in Chrome’s DevTools the other day and almost jumped out of my seat with pure joy. Not only was I completely unaware that such a thing exists, but it was better than what I could’ve hoped: it lets you control and manipulate CSS animations and visualize how everything works under the hood.

To access the panel, head to More Tools → Animations in the top right-hand menu when DevTools is open:

Many of the tutorials I found about this were pretty complicated, so let’s take a step back and look at a smaller example to begin with: here’s a demo where the background-color of the html element will transition from black to orange on hover:

html {
  cursor: pointer;
  background-color: #333;
  transition: background-color 4s ease;
}

html:hover {
  background-color: #e38810;
}

Let’s imagine that we want to nudge that transition time down from 4s. It can get pretty annoying just bumping that number up and down in the element inspector. I typically would’ve opened up DevTools, found the element in the DOM and then ever-so-slowly manipulate it by typing in a value or using the keyboard directional keys. Instead, we can fire up that demo, open DevTools, and switch to the Animation tab which ought to look something like this:

By default, Chrome will be "listening" for animations to take place. Once they do, they’ll be added to the list. See how those animation blocks are displayed sort of like an audio wave? That’s one frame, or act, of an animation and you can see on the timeline above it each frame that follows it. On an animation itself, the inspector will even show us which property is being changed, like background-color or transform. How neat is that?

We can then modify that animation by grabbing that bar and moving it about:

...and it updates the animation right away — no more clicking and editing an animation the old way! Also, you might’ve noticed that hovering over an animation frame wil highlighted the element that’s being animated in blue. This is handy if you’re editing a complex animation and forget what that crazy weird pseudo element does. If you have multiple animations on a page, then you can see them all listed in that section just like in this demo:

What we’re doing here is animating both the .square and the .circle when hovering on the html element, so there’s effectively two separate divs being animated in the same time frame — that’s why you can see them in the same section just like that.

I can see that inspecting animations in this way could be super useful for tiny icon design, too. Take this pen of Hamburger menu animations by Jesse Couch where you might want to slow everything down to get things just right. Well, with the animation inspector tool you can do exactly that:

Those buttons in the top left-hand corner will control the playback speed of the animation. So hitting 10% will slow things to a crawl — giving you enough time to really futz with things until they’re perfect.

I’ve focused on Chrome here but it’s not the only browser with an animation inspector — Firefox’s tool is in every way just as useful. The only immediate difference I found was that Chrome will listen for any animations on a page and will display them once their captured. But, with Firefox, you have to inspect the element and only then will it show you the animations attached to that element. So, if you’re doing super complex animations, then Chrome’s tool might be a smidge more helpful.

Animation Inspector Documentation

• Walkthrough on Google Developers
• Animation inspector in Firefox – MDN

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