This was done entirely as an experiment to help me learn Box2D by way of rewriting/porting Seth Ladd's examples starting here:
http://blog.sethladd.com/2011/08/box2d-orientation-for-javascript.html
Only the examples that were significant pieces of changed code were ported.
This is still a work in progress, getting it on github is for my own organization.
Relevant licenses should still be intact from the original source:
https://github.com/sethladd/box2d-javascript-fun
Anything new that doesn't fall under derivative is BSD licensed.