[Being an optimized version][link] of the [original Box2d-JS port][orig], which is based on Box2d 1.4. Does your head hurt yet?
This version depends on jQuery instead of Prototype, and uses SVG instead of the Canvas tag. [Check out the demo.][demo]
[link]: http://github.com/hrj/box2d-js “hrj’s box2d-js at master – GitHub”
[demo]: http://lavadip.com/box2d_demo/index.html “Box2d Demo”
[orig]: http://box2d-js.sourceforge.net/ “Original Box2d Port”