Webshim is a polyfill library that enables you to reliably use HTML5 features across browsers, even if native support is lacking.
JavaScript Libraries and Functions
A lightweight vanilla JavaScript script that detects the :focus-within pseudo-selector and applies a standard CSS class as a fallback, if needed.
Hosted polyfill script.
JavaScript Libraries and Functions · JavaScript Library
Polyfill for webcomponents.
JavaScript Libraries and Functions · Framework
Sticky polyfill.
Responsive image polyfill.
JavaScript Libraries and Functions · Compatibility
A polyfill for ES6-style Promises.
A window.fetch JavaScript polyfill.
Polyfill promises system.
AdapterJS Javascript Polyfill and Utilities for WebRTC.
matchMedia polyfill for testing media queries in JS.
Polyfill to remove click delays on browsers with touch UIs.
Widgets · Mobile
A fast & lightweight polyfill for min/max-width CSS3 Media Queries (for IE 6-8, and more)
Polyfills import maps and other ES Modules features on top of the baseline native ESM support in browsers.