Before you start
Learning Box2D in just a few pages is not possible. A whole book is what you will need to start mastering it.
Tip
For an in-depth understanding of Box2D, you can find my book, Box2D for Flash Games, at https://www.packtpub.com/game-development/box2d-flash-games.
Anyway, this chapter will give you the bare bones to add physics to your games. Although experienced Box2D users may find some concepts such as collision detection covered in a less-than-perfect way, in the end, it works and that's what really matters in the scope of this chapter: giving you the knowledge to start learning Box2D and include it into your Cocos2d-JS projects.