Additive Animation with the Web Animations API

These features have not landed in any stable browsers at the time of writing. However, everything discussed is already in Firefox Nightly by default and key parts are in Chrome Canary (with the Experimental Web Platform Features flag enabled), so I recommend using one of those browsers (when reading this article) to see as many of the features in action as possible.
Regardless your preferred method of animation on the web, there will be times that you need to animate …

Additive Animation with the Web Animations API is a post from CSS-Tricks

Link: https://css-tricks.com/additive-animation-web-animations-api/