JavaScript libraries and frameworks

• Prototype
• Script.aculo.us
• YUI (Yahoo! User Interface)
• Dojo Toolkit
• ExtJS
• MooTools
• MochiKit
• jQuery
• JavaScript InfoVis Toolkit: data visualization
• D3.js: data visualization
• Modernizr: tests for browser features
• Sizzle: a lightweight CSS selector engine
• Underscore.js: utility functions
• Node.js: server-side JavaScript
• Joose: supports object-oriented programming paradigms
• qooxdoo
• Bootstrap: supports responsive design
• Bootbox: adds dialog boxes to Bootstrap
• jQuery Waypoints: supports actions based on page scrolling
• turn.js: creates a page flipping effect (uses jQuery)
• less.js: extends CSS using JavaScript