Rainbow is a code syntax highlighting library written in Javascript.
It was designed to be lightweight (1.4kb), easy to use, and extendable.
It is completely themable via CSS.

Handsontable is a minimalistic approach to Excel-like table editor in HTML & jQuery. Now with column and row headers!

Superheroic JavaScript MVC Framework

jsmad is a pure javascript MP3 decoder, based on libmad, with an ID3 decoder written from scratch.

Principles of Writing Consistent, Idiomatic JavaScript

A JavaScript framework for creating ambitious web applications

DOM Monster is a cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on, and give you its bill of health.

Add Clippy or his friends to any website for instant nostalgia.

Build Desktop Applications for Linux, Mac and Windows using HTML, CSS and Javascript

Meteor is an ultra-simple environment for building modern websites.

Filtrr2 is a JavaScript image manipulation library. Think of it as Instagram filters on the browser. It uses the <canvas> element to paint filtered pictures in the place of normal pictures on your website.

Beautifully crafted timelines that are easy, and intuitive to use.

Modest Maps is a small, extensible, and free library for designers and developers who want to use interactive maps in their own projects.

Fantastic Micro-Frameworks and Micro-Libraries for Fun and Profit!

Morris.js is a lightweight library that uses jQuery and Raphaël to make drawing time-series graphs easy.

A Modern, Lightweight Open-Source JavaScript Library for Interactive Maps

Build responsive, mobile-first projects on the web with the world's most popular front-end component library.

Bootstrap is an open source toolkit for developing with HTML, CSS, and JS. Quickly prototype your ideas or build your entire app with our Sass variables and mixins, responsive grid system, extensive prebuilt components, and powerful plugins built on jQuery.

Slides

A framework for easily creating beautiful presentations using HTML. Check out the live demo.

reveal.js comes with a broad range of features including nested slides, Markdown contents, PDF export, speaker notes and a JavaScript API. There's also a fully featured visual editor and platform for sharing reveal.js presentations at slides.com.

The chromeless project is an experiment into making it possible to build a web browser using only web technologies, like HTML, JavaScript, and CSS.

ECMAScript 5 compatibility table