Oimo.js
Lightweight 3d physics engine for javascript
LABjs
Loading And Blocking JavaScript: On-demand parallel loader for JavaScript with execution order dependencies
Infinity
UITableViews for the web.
Glslify
A node.js-style module system for GLSL!
Spine
Lightweight MVC library for building JavaScript applications
Rainbow
Simple syntax highlighting library written in javascript
Speak.js
Text-to-Speech in JavaScript using eSpeak
ICanHaz.js
A clean solution for templating with Mustache.js and jQuery or Zepto
Stretchy
Form element autosizing, the way it should be.
Caman Js
Pure Javascript HTML5 (Ca)nvas (Man)ipulation
Brick
UI Web Components for Mobile Web Apps
Display Js
A simple JavaScript framework for building ambitious UIs 😊
Carlo
Web rendering surface for Node applications
Melon JS
a fresh & lightweight javascript game engine
Lazy.js
Like underscore.js, but lazier
Walkway
An easy way to animate SVG elements.
JS xls
Javascript XLS (Excel 97-2004 spreadsheet) parser and (one day) writer