[coffeecodecouch]

If you want to use box2d, use box2dweb[0]. It's much smaller and faster and is actually up to date. However if you want your game to run smoothly on mobile phones your best bet is Chimpunk-js[1].

[0] https://code.google.com/p/box2dweb/

[1] https://github.com/josephg/Chipmunk-js