Web Client Libraries and Frameworks
jQuery
jQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development.
Underscore.js
Underscore is a utility-belt library for JavaScript that provides a lot of the functional programming support that you would expect in Prototype.js (or Ruby), but without extending any of the built-in JavaScript objects. It's the tie to go along with jQuery's tux.
Modernizr
Modernizr is your starting point for making the best websites and applications that work exactly right no matter what browser or device your visitors use.
Knockout.js
Simplify dynamic JavaScript UIs by applying the Model-View-View Model (MVVM)
Backbone.js
Backbone supplies structure to JavaScript-heavy applications by providing models with key-value binding and custom events, collections with a rich API of enumerable functions, views with declarative event handling, and connects it all to your existing application over a RESTful JSON interface.
JS and CSS Toolkits
Google Libraries API
The Google Libraries API is a content distribution network and loading architecture for the most popular, open-source JavaScript libraries.
CoffeeScript
CoffeeScript is a little language that compiles into JavaScript. Underneath all those awkward braces and semicolons, JavaScript has always had a gorgeous object model at its heart. CoffeeScript is an attempt to expose the good parts of JavaScript in a simple way. Also see:
dart
lesscss
LESS extends CSS with dynamic behavior such as variables, mixins, operations and functions. LESS runs on both the client-side (IE 6+, Webkit, Firefox) and server-side, with Node.js and Rhino.
twitter bootstrap
Simple and flexible HTML, CSS, and Javascript for popular user interface components and interactions.
requirejs.org
JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, like Rhino and Node. Using a modular script loader like RequireJS will improve the speed and quality of your code.
JS InfoVis Libraries
Processing.js
Processing.js is the sister project of the popular Processing visual programming language, designed for the web. Processing.js makes your data visualizations, digital art, interactive animations, educational graphs, video games, etc. work using web standards and without any plug-ins.
d3.js
D3.js is a small, free JavaScript library for manipulating documents based on data and visualization framework. (From the authors of the now inactive
protovis.)
Flot
Flot is a pure Javascript plotting library for jQuery. It produces graphical plots of arbitrary datasets on-the-fly client-side.
arborjs
Arbor is a graph visualization library built with web workers and jQuery. Rather than trying to be an all-encompassing framework, arbor provides an efficient, force-directed layout algorithm plus abstractions for graph organization and screen refresh handling.
Raphaël
Raphaël is a small JavaScript library that should simplify your work with vector graphics on the web. If you want to create your own specific chart or image crop and rotate widget, for example, you can achieve it simply and easily with this library.
JS Math Libraries
MathJax
MathJax is an open source JavaScript display engine for mathematics that works in all modern browsers.
jStat
jStat is a statistical library written in JavaScript that allows you to perform advanced statistical operations without the need of a dedicated statistical language (i.e. MATLAB or R).
On the Radar
Stripe.js
Stripe.js lets you build your own payment forms while still avoiding most PCI requirements. Credit cards go directly to Stripe's secure environment, and never hit your servers.
three.js
Javascript 3D Engine. The aim of the project is to create a lightweight 3D engine with a very low level of complexity.
speak.js
Enables text-to-speech on the web using only JavaScript and HTML5. A port of the eSpeak speech synthesizer from C++ to JavaScript using Emscripten. Online demo:
http://syntensity.com/static/espeak.html
Blog Posts Etc
Knockout.js vs. Backbone.js
Introducing Knockout, a UI library for JavaScript
A re-introduction to JavaScript (mozilla.org)
JavaScript for C# developers: writing a library
20 Fresh JavaScript Data Visualization Libraries