Vex : Vex is a modern dialog library which is highly configurable, easily stylable, and gets out of the way. You'll love vex because it's tiny (6kb minified...
Headroom.js : Headroom.js is a lightweight, high-performance JS widget (with no dependencies!) that allows you to react to the user's scroll.
ProseMirror : In-browser structured text editing component. A toolkit for building rich-text editors on the web.
Zero Clipboard : The Zero Clipboard library provides an easy way to copy text to the clipboard using an invisible Adobe Flash movie, and a JavaScript interface. The "Z...
Crafty : JavaScript Game Engine, HTML5 Game Engine