Framework or Library

Canvas Manipulation

• PaperJS - The Swiss Army Knife of Vector Graphics Scripting

Charts

• flot - Attractive JavaScript charts for jQuery
• chartist-js - Simple responsive charts
• dc.js - Multi-Dimensional charting built to work natively with crossfilter rendered with d3.js
• charted - A charting tool that produces automatic, shareable charts from any data file
• Sigma - A JavaScript library dedicated to graph drawing
• nvd3 - A reusable charting library written in d3.js
• d3.chart - A framework for creating reusable charts with d3.js
• arbor - a graph visualization library using web workers and jQuery
• echarts - Enterprise Charts | Github pages
• c3 - A D3-based reusable chart library
• Chart.js - Simple HTML5 Charts using the <canvas> tag

Date

• xdate - A Modern JavaScript Date Library
• Datejs - A JavaScript Date Library
• Timeago - Timeago is a jQuery plugin that makes it easy to support automatically updating fuzzy timestamps
• moment - Parse, validate, manipulate, and display dates in javascript

Desktop Tool

• nw.js - Call all Node.js modules directly from DOM and enable a new way of writing applications with all Web technologies
• electron - Build cross platform desktop apps with web technologies

DOM Manipulation

• jQuery - jQuery JavaScript Library
• ractive - Next-generation DOM manipulation
• sizzle - A sizzlin' hot selector engine.
• HTML - A simple, extensible way to work directly with the DOM.
• dojo - The Dojo Toolkit core library.
• mootools - MooTools Core Repository
• yui3 - A library for building richly interactive web applications.

Functional Programming

• Lodash - A JavaScript utility library delivering consistency, modularity, performance, & extras.
• lazy.js - Like Underscore, but lazier

Game Development or Webgl

• Phaser - A framework for desktop/mobile web browsers, supporting Canvas and WebGL rendering

Graphics or data visualization

• vega - A visualization grammar.
• Leaflet - JavaScript library for mobile-friendly interactive maps
• polymaps - Polymaps is a free JavaScript library for making dynamic, interactive maps in modern web browsers.
• raw - The missing link between spreadsheets and vector graphics
• dygraphs - Interactive visualizations of time series using JavaScript and the HTML canvas tag
• lumify - open source big data integration, analytics, and visualization
• kartograph.js - Open source JavaScript renderer for Kartograph SVG maps
• envisionjs - Dynamic HTML5 visualization
• exhibit - Publishing Framework for Large-Scale Data-Rich Interactive Web Pages
• modestmaps-js - Modest Maps javascript port
• jit - The JavaScript InfoVis Toolkit provides tools for creating Interactive Data Visualizations for the Web
• crossfilter - Fast n-dimensional filtering and grouping of records.
• nodebox - Interactive, hackable graphic design application
• recline - A simple but powerful library for building data applications in pure Javascript and HTML.
• ProcessingJS - A port of the Processing Visualization Language

Hybrid Development

• OnsenUI - Custom Elements-Based HTML5 UI Framework for Building Your Mobile Front End
• mobile-angular-ui - Angular.js Mobile UI Framework with Bootstrap 3
• app - Instant mobile web app creation
• jquery-mobile - jQuery Mobile Framework
• Lunga.js - A framework for developers who want to design, build and share cross device applications.
• jo - Jo (0.5.0) is a thin (~16K) candy shell for making HTML5 apps.
• junior - A front-end framework for building html5 mobile apps with a native look and feel.
• chocolatechip-ui - Mobile Web App Framework
• ratchet - Build mobile apps with simple HTML, CSS, and JavaScript components.
• ionic - Advanced HTML5 mobile development framework and SDK

Inline Editor

• medium.js - A tiny JavaScript library for making contenteditable beautiful (Like Medium's editor)
• Ace - Ace (Ajax.org Cloud9 Editor)
• CodeMirror - In-browser code editor
• quill - A cross browser rich text editor with an API
• pen - enjoy live editing (+markdown)
• EpicEditor - An Embeddable JavaScript Markdown Editor

Just Awesome

• Tangle - a JavaScript library for reactive documents
• Clusterise - Tiny vanilla JS plugin to display large data sets easily
• Behave.js - A lightweight, cross browser library for adding IDE style behaviors to plain text areas
• zoom.js - Medium's Image Zoom for jQuery
• underscore.js - JavaScript's utility _ belt
• hammer.js - A javascript library for multi-touch gestures
• page.js - Micro client-side router inspired by the Express router
• TimelineJS - TimelineJS: A Storytelling Timeline built in JavaScript.
• highlight.js - Javascript syntax highlighter
• prism - Lightweight, robust, elegant syntax highlighting.
• Impress - framework based on the power of CSS3 transforms and transitions in modern browsers
• Snap.js - A Library for creating beautiful mobile shelfs in Javascript (Facebook and Path style side menus)

Math

• Math.js - An extensive math library for JavaScript and Node.js
• numbers.js - Advanced Mathematics Library for Node.js and JavaScript
• science.js - Scientific and statistical computing in JavaScript
• bignumber.js - A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic

Mobile Related

• Swipe - Swipe is the most accurate touch slider.
• Snap.js - A Library for creating beautiful mobile shelfs in Javascript

Parser

• PDFJS - PDF Reader in JavaScript
• esprima - ECMAScript parsing infrastructure for multipurpose analysis
• shift-parser-js - ECMAScript parser that produces a Shift format AST
• PapaParse - Fast and powerful CSV (delimited text) parser that gracefully handles large files and malformed input
• jBinary - High-level API for working with binary data.

SVG Manipulation

• Raphael - Simplify your work with vector graphics on the web
• Raphael - Simplify your work with vector graphics on the web

Testing

• jasmine - DOM-less simple JavaScript testing framework
• mocha - mocha - simple, flexible, fun javascript test framework for node.js & the browser.
• buster - A powerful suite of automated test tools for JavaScript.
• karma - Spectacular Test Runner for JavaScript
• jest - Painless JavaScript Unit Testing built on top of the Jasmine test framework.
• qunit - An easy-to-use JavaScript Unit Testing framework.
• phantomjs - Scriptable Headless WebKit

Web development or MVC

• Angular - HTML enhanced for web apps!
• Backbone - Backbone.js gives structure to web applications
• Ampersand - A highly modular, loosely coupled, non-frameworky framework
• Vue.js - Vue.js, JavaScript framework for building user interfaces.
• Spine - Lightweight MVC library for building JavaScript applications
• Aurelia - A Framework that leverages simple conventions to empower your creativity
• Ampersand - A highly modular, loosely coupled, non-frameworky framework
• winjs - A UI toolkit for modern browsers
• Riotjs - A React- like, 3.5KB user interface library