Cocos2D-html5 is the latest spin off from Cocos2d-x team. It is a HTML5 version of Cocos2d-x project and written in Javascript for HTML5 compliant browsers. The API is derived from Cocos2d-x, therefor if you have any experience in Cocos2d game engines, you already know how to use Cocos2d-html5.
Cocos2d-html5 is an open-source web 2D game framework, released under MIT License.
Our focus for Cocos2d-html5 development is around making Cocos2d-x cross platforms between browsers and native application. Because Cocos2D-html5 is based on web, you can write your app on any platform as long as you have access to a text editor, and because its web based, your app can be run on any device that have access to a web browser (HTML5 compliant one)!
On top of the framework provided by Cocos2d-html5, games can be written in Javascript, using API that is COMPLETELY COMPATIBLE with that of Cocos2d-x javascript binding. So that Cocos2d-html5 games can be easily ported to Cocos2d-x JSB without or with little modification.