HTML5 Polyfills

Instead of offering an HTML5 player to modern browsers and a totally separate Flash player to older browsers, MediaElement.js upgrades them with custom Flash and Silverlight plugins that mimic the HTML5 MediaElement API

A jQuery plugin, (and now a Zepto plugin,) jPlayer allows you to rapidly weave cross platform audio and video into your web pages

Using HTML5 and Flash, SoundManager 2 provides reliable cross-platform audio under a single JavaScript API.

LeanBack Player is a Javascript based HTML5 Video and Audio Media Player UI that uses build-in HTML5 <video> and <audio> element functionality of standard browsers, platforms and devices

PIE makes Internet Explorer 6-9 capable of rendering several of the most useful CSS3 decoration features including border-image

PIE makes Internet Explorer 6-9 capable of rendering several of the most useful CSS3 decoration features including border-radius

PIE makes Internet Explorer 6-9 capable of rendering several of the most useful CSS3 decoration features including box-shadow

Javascript polyfill for CSS3 box-sizing: border-box. For IE6 and IE7

border-box polyfill for SASS/Compass. Outputs equivalent CSS for IE6 & 7

FlashCanvas is a JavaScript library which adds the HTML5 Canvas support to Internet Explorer. It renders shapes and images via Flash drawing API. It supports almost all Canvas APIs and, in many cases, runs faster than other similar libraries which use VML or Silverlight.

ExplorerCanvas brings the canvas functionality to Internet Explorer. To use, web developers only need to include a single script tag in their existing web pages

This project successfully uses Silverlight as a rendering engine to implement HTML 5 <canvas> support in IE6~IE8. It also enables onload=".." attribute support for native canvas renderers for 'this' context object activation.

fxCanvas is an implementation of the HTML5 Canvas element for Internet Explorer (two-dimensional graphics only).

KineticJS is an HTML5 Canvas JavaScript framework that enables high performance animations, transitions, node nesting, layering, filtering, caching, event handling for desktop and mobile applications, and much more

An implementation of the HTML5 canvas text drawing methods for older browser

classList.js is a cross-browser JavaScript shim that fully implements element.classList

Implements a CORS-compliant cross-domain XMLHttpRequest with postMessage. Note that sites being requested must have a pmxdr host

libxdr is a library that implements a cross-browser (postMessage-supporting browsers only) cross-domain request constructor, XDR, using pmxdr

Simple polyfill that allows browsers without support for cross-origin XMLHttpRequests to do so via postMessage.

Provides XHR API using Flash transport mechanism. Target server must have a crossdomain.xml policy file

Enables cross-browser* html5 datalist for inputs, by first testing for a native implementation before building one.

Webshims Lib is a modular capability-based polyfill-loading library, which focuses on accurate implementations of stable HTML5 features, so that developers can write modern, interoperable and robust code in all browsers. It is built on top of jQuery and Modernizr

Add dataset support to elements

Implementation of HTML 5 dataset (data-* attributes) support that almost conforms to the HTML 5 spec* and works in Firefox 1.5+, Opera 9.5+, Safari, and Google Chrome

This plugin polyfills <details>/<summary> HTML elements and adds the appropriate ARIA annotations for optimal accessibility.

This jQuery based polyfill makes <details>/<summary> ready for use in most browsers.

Claims to be better than all the four above

Implements the DOM Level 3 API across all modern browsers and extends the API with extremely useful functions

Normalizing the DOM across all modern browsers. DOM-shim provides compatibility shims so that modern browsers behave as closely to DOM4 as possible

ES5 and DOM4 shim for all browsers with IE6 and IE7 support

New DOM 4 Entries: prepend, append, before, after, replace and remove W3C Draft compatible and fully tested

W3C Events, included custom bubbling events, for IE8

One of the lesser known HTML5 JavaScript goodies is the document.head DOM tree accessor, which is a more efficient (and easier to type) alternative to document.getElementsByTagName('head')[0]

JavaScript + DOM implementation of W3C URL API

IE8 Shim for DOMImplementation.prototype.createDocument (does not support doctype argument nor wrap the resulting document to support all DOM methods and properties; mostly for loading XML

es5-shim.js and es5-shim.min.js monkey-patch a JavaScript context to contain all EcmaScript 5 methods that can be faithfully emulated with a legacy JavaScript engine

Xccessors (cross-browser accessors) is a JavaScript shim that implements the legacy or standard methods for defining and looking up accessors (getters and setters) of objects.

Transitioning Existing Code to the ES5 Getter/Setter APIs

JSON 3 is a modern JSON implementation compatible with a variety of JavaScript platforms, including Internet Explorer 6, Opera 7, Safari 2, and Netscape 6

ddr-ecma5 is a JavaScript library which brings the ECMAScript 5 extensions to any browser. It includes set of ECMAScript 5 methods to Object, Array, String, Date and Function objects which are possible to be implemented with ECMAScript 3 features.

Enables use of modern JavaScript by augmenting built in objects with the latest JavaScript methods.

Provides compatibility shims so that legacy JavaScript engines behave as closely as possible to ECMAScript 6

Use the new Map, Set, and WeakMap from the upcoming ES6 standard right now! This shim provides full functionality for these collections and delivers the benefits of using them

This is a destructive shim that implements the ES6 Map specification as closely as possible

Blitz-Collections provides ECMAScript 6 (aka ECMAScript Harmony aka ECMAScript Next) collections to ECMAScript 5 compliant environments. This includes Map, WeakMap and Set

Dropfile is a shim which uses Silverlight to recreate the part of the HTML5 FileAPI which lets us drag files into the IE browser and read em'

FileSaver.js implements the W3C saveAs() FileSaver interface in browsers that do not natively support it. There is a FileSaver.js demo that demonstrates saving various media types

mOxie is combined name for XHR2 and File API pollyfills that has been extracted from Plupload in order to make it more flexible and give it opportunity for further growth

This library is a JavaScript + Flash library that allows you to read files client side using standart File API. It moves a transparent flash button over any DOM element and gives it a HTML 5 file input behavior

A set of javascript tools for working with files. Multiupload, drag'n'drop and chunked file upload. Images: crop, resize and auto orientation by EXIF

idb.filesystem.js is a well tested JavaScript polyfill implementation of the HTML5 Filesystem API. It is intended for browsers that do not support the API natively.

This polyfill takes the official CSS filters syntax and translates it to the different equivalent techniques that the browsers know for those effects

*There is no polyfill for the new spec

Webshims Lib is a modular capability-based polyfill-loading library, which focuses on accurate implementations of stable HTML5 features, so that developers can write modern, interoperable and robust code in all browsers

a JavaScript library that allows you to use the HTML5 Forms chapters new field input types, attributes and constraint validation API in non-supporting browsers

Best practice realtime HTML5 form validation for jQuery. Works on all popular browsers, including old ones like IE6

Simple wrapper for cross-browser usage of the JavaScript Fullscreen API, which lets you bring the page or any element into fullscreen. Smoothens out the browser implementation differences, so you don't have too

This library provides a consistent Geolocation API for miscellaneous web browsers and also acts as polyfill

PIE makes Internet Explorer 6-9 capable of rendering several of the most useful CSS3 decoration features including gradients

History.js gracefully supports the HTML5 History/State APIs (pushState, replaceState, onPopState) in all browsers. Including continued support for data, titles, replaceState. Supports jQuery, MooTools and Prototype. For HTML5 browsers this means that you can modify the URL directly, without needing to use hashes anymore. For HTML4 browsers it will revert back to using the old onhashchange functionality

This Javascript library provides an emulation of HTML5 History API for older browsers

pjax is a jQuery plugin that uses ajax and pushState to deliver a fast browsing experience with real permalinks, page titles, and a working back button

This script is the defacto way to enable use of HTML5 sectioning elements in legacy Internet Explorer

While most browsers work all right with the new semantic elements of HTML5, they don’t add the ARIA accessibility attributes that the specification demands. This small JavaScript adds those attributes to enhance accessibility of web sites

This IndexedDB polyfill exposes the IndexedDB API in unsupported browsers using WebSQL. This shim is basically an IndexedDB-WebSql adapter

A polyfill for implementing the HTML5 <input type="number"> element in browsers that do not currently support it

The HTML5 range input is now powered by a jQuery Tools cross-browser implementation that can be skinned with CSS. For browsers that implement range inputs natively, the input field's type is changed to text so that the native version does not get in the way

An Unobtrusive Accessible Slider script that can also be used as an HTML5 Input Range polyfill solution

A jQuery plugin that enables HTML5 placeholder behavior for browsers that aren’t trying hard enough yet

Placeholder Enhanced enhance the use of HTML5 placeholder attribute providing cross-browser support & styling

A jQuery plugin that polyfills the HTML5 "placeholder" attribute

Support certain HTML 5 attributes with javascript, but only if the browser doesn't already support them

A jQuery plugin that provides failover for browsers that don't support the native HTML5 placeholder attribute. Placeholders allow text inputs and textareas to display a placeholder message until they get focus, at which point the input box is set to empty

Placeholders.js is a polyfill (or shim, or whatever you like to call it) for the HTML5 placeholder attribute, as defined in the HTML5 draft specification. Placeholder attributes are valid on input elements of various types and textarea elements

When you focus a field it keeps the placeholder text until you start typing. This keeps users from forgetting what the field is before they start typing

JSON 3 is a modern JSON implementation compatible with a variety of JavaScript platforms, including Internet Explorer 6, Opera 7, Safari 2, and Netscape 6

CupCake.js is a real HTML5 inspired javascript library which manage both new storage components shipped with HTML5 ,session and local storage

Test whether a CSS media type or media query applies

A fast & lightweight polyfill for min/max-width CSS3 Media Queries (for IE 6-8, and more)

Make CSS3 Media Queries work in all browsers (JavaScript library)

This library adds media queries support to browsers that don't support it (like Internet Explorer 5.5-8)

Some media query and cross-browser responsive design helpers, abstracted from jQuery Mobile

MicrodataJS is a jQuery plugin that provides an API for accessing Microdata inspired by (but by necessity slightly different from) the native DOM API

Implementation of the HTML5 Microdata specification for all browsers (including IE8, IE7, IE6 with es5 and DOM shims)

Supports: column-count, column-width, column-gap, column-rule

A polyfill for the 'reversed' attribute for ordered lists, new in HTML5, but currently no browser support

Pointer Events Polyfill is a short javascript library which adds support for the style attribute "pointer-events: none" to browsers without this feature (namely, MS IE)

easyXDM is a Javascript library that enables you as a developer to easily work around the limitation set in place by the Same Origin Policy, in turn making it easy to communicate and expose javascript API’s across domain boundaries

CSSRegions.js is an experimental polyfill that uses JavaScript to bring CSS Regions functionality to browsers that don't support the feature

requestAnimationFrame polyfill

selectivizr is a JavaScript utility that emulates CSS3 pseudo-classes and attribute selectors in Internet Explorer 6-8

Fast and lightweight querySelector[All]/getElementsByClassName/matchesSelector

Partial support for SVG 1.1, SVG Animation (SMIL), Fonts, Video and Audio, DOM and style scripting through JavaScript, and more in a small library

Small JavaScript library that should simplify your work with vector graphics on the web.

canvg is a SVG parser and renderer. It takes a URL to a SVG file or the text of an SVG file, parses it in JavaScript, and renders the result on a Canvas element. The rendering speed of the examples is about as fast as native SVG.

Ample SDK is a standard-based cross-browser JavaScript UI Framework for building Rich Internet Applications. It employs XML technologies (such as XUL, SVG or HTML5) for UI layout

The 'SIE' is an Open Source rendring engine written in JavaScript to display a W3C standard Scalable Vector Graphics (i.e. SVG). SVG is a language for drawing a vector graphics like HTML. It's used in Inkscape, Illustlator and so on.

Fabric.js is a framework that makes it easy to work with HTML5 canvas element. It is an interactive object model on top of canvas element. It is also an SVG-to-canvas parser.

Transformie is a javascript plugin that comes in less than 5k that you embed into web pages and that brings you CSS Transforms by mapping the native IE Filter API to CSS trandforms as proposed by Webkit

Cross Browser CSS Transforms – even in IE

MediaElement.js upgrades them with custom Flash and Silverlight plugins that mimic the HTML5 MediaElement API

Video.js is a JavaScript and CSS library that makes it easier to work with and build on HTML5 video

LeanBack Player is a Javascript based HTML5 Video and Audio Media Player UI that uses build-in HTML5 <video> and <audio> element functionality of standard browsers, platforms and devices

Video for Everybody is simply a chunk of HTML code that embeds a video into a website using the HTML5 <video> element, falling back to Flash automatically without the use of JavaScript or browser-sniffing

A polyfill for CSS units vw, vh & vmin and now some media queries to boot. Works in IE5.5 and Opera Mini

JebGL is a piece of Javascript which lets you run your WebGL apps in browsers lacking WebGL support without having to modify your existing code! Behind the scenes JebGL uses a fallback Java applet to emulate the WebGL canvas if needed, and the Java applet runs hardware accelerated on all platforms using JOGL

This project is an attempt at writing a pure-JavaScript WebGL compatibility layer. The goal is to produce a library that emulates WebGL functionality by wrapping around a Canvas2D context

Implements a WebGL stack (WebGL, OpenGL) using pure Javascript and Canvas element. This allows client applications to support browsers that implement Canvas, but do not implement WebGL (Internet Explorer 9+), or client machines that do not have sufficient graphic drivers

IEWebGL is a plugin for Microsoft Internet Explorer web browser, that adds support for WebGL

Socket.IO aims to make realtime apps possible in every browser and mobile device, blurring the differences between the different transport mechanisms. It's care-free realtime 100% in JavaScript

Using Atmosphere’s JQuery Plug In to build applications supporting both Websocket and Comet

The Portal is a server agnostic JavaScript library that not just provides a socket for browser-based applications that need two-way communication with servers, but also aims to utilize a full duplex connection for modern web application development

Web browser polyfill that implement the WebRTC DataChannel API over a websocket