There are three ways to get a copy of the polyfill:

1. Download and use the web-animations.min.js file directly from this repository
2. Using npm: Add web-animations-js to your package.json
3. Using Bower: Add web-animations/web-animations-js to your bower.json

The polyfill is supported on modern versions of all major browsers, including:

• Chrome 56+
• Firefox 27+
• IE10+ (including Edge)
• Safari (iOS) 7.1+
• Safari (Mac) 9+

In particular, the polyfill requires requestAnimationFrame. If your browser does not have requestAnimationFrame, consider loading a requestAnimationFrame polyfill first (example).

When the polyfill runs on a browser that implements Element.animate() and Animation playback control, it will detect and use the underlying native features for better performance.

The web-animations.min.js polyfill target tracks the Web Animations features that are supported natively in browsers. These include:

• Element.animate()
• Timing input (easings, duration, fillMode, etc.) for animation effects
• Playback control (play, pause, reverse, currentTime, cancel, onfinish)
• Support for animating CSS properties

The polyfill will automatically detect the correctly prefixed name to use when writing animated properties back to the platform. Where possible, the polyfill will only accept unprefixed versions of experimental features. For example:

will work in all browsers that implement a conforming version of transform, but

will not work anywhere.

When we make a potentially breaking change to the polyfill's API surface (like a rename) we will, where possible, continue supporting the old version, deprecated, for three months, and ensure that there are console warnings to indicate that a change is pending. After three months, the old version of the API surface (e.g. the old version of a function name) will be removed. If you see deprecation warnings, you can't avoid them by not updating.