Assemble
Static site generator for Node.js, Grunt.js, and Yeoman (and soon, Gulp), using the Handlebars template engine. Used by Zurb Foundation, Zurb Ink, H5BP/Effeckt, Less.js / lesscss.org, Topcoat, Web Experience Toolkit, and hundreds of other projects to build sites, themes, components, documentation, blogs and gh-pages. Pull requests welcome, stars appreciated!
Please Js
JavaScript Library for creating random pleasing colors and color schemes
Humanize
A simple utility library for making the web more humane. #hubspot-open-source
Pjs
Classes for javascript that don't suck.
Parsimmon
A monadic LL(infinity) parser combinator library for javascript
Hello.js
A Javascript RESTFUL API library for connecting with OAuth2 services, such as Google+ API, Facebook Graph and Windows Live Connect
Purl
A JS utility for for parsing URLs and extracting information out of them.
Olly.js
Translate URLs into Rich Media
Numeric
Numerical analysis in Javascript
Medium Editor Insert Plugin
jQuery insert plugin for MediumEditor (Medium.com WYSIWYG editor clone)
Kartograph.js
Open source JavaScript renderer for Kartograph SVG maps
Probability.js
Probability.js makes it easy to call JavaScript functions by probability in Node.js and the browser.
Timer.js
Timer.js is a periodic timer for Node.js and the browser.
Trip.js
Trip.js is a plugin that can help you customize a tutorial trip easily with more flexibilities. ( Based on jQuery )
LZ String
LZ-based compression algorithm for JavaScript
jQuery Migrate
APIs and features removed from jQuery core
Wordcount.js
Calculate file newlines, word, and byte counts on client side using HTML5 File API. (Emulates Linux's wc command)