HTML5 Cross Browser Polyfills - GitHub
A sprawling, community-maintained directory of shims, polyfills, and fallback libraries for bringing HTML5, CSS3, and ECMAScript features to browsers that lack native support, curated by Paul Irish. The premise is that developers should code against the standard APIs and let scripts fill the gaps, so nothing needs rewriting as users move to native implementations. It is organized by feature area, including SVG, canvas, storage, forms, video and audio, WebSockets, History, CSS layout and selectors, and ES5/ES6, with short notes on each library's approach (Flash, VML, or pure JS) and caveats like deprecation or non-standard APIs, plus pointers to Modernizr, HTML5PLEASE, and Polyfiller for related needs.