Cocos2d-JS is the HTML5 version of Cocos2d-x, includes Cocos2d-html5 and Cocos2d-x JavaScript Binding (JSB). Using Cocos2d-JS, you can write games in JavaScript and run your games on browsers that support HTML5.
Cocos2d-JS is an open source game engine for web games and native games. It has a high performance, is user-friendly and supports multi-platform development. Supported platforms include web, Android, iOS, Windows Phone 8, Mac, Windows, etc.