If you ask me what the biggest revolution in casual gaming is, no doubt I'll say physics engines. A lot of top-selling casual games such as Crayon Physics, Totem Destroyer, Crush the Castle, Angry Birds, Tiny Wings, just to mention a few use physics engines to add a realistic behavior that wouldn't be possible without such engines.
The most popular among physics engines in the 2D world is Box2D, initially written in C++, then ported to all major languages, including JavaScript.
Cocos2d-JS supports Box2D, and this chapter will cover the creation of a physics game, including these concepts:
Configuring and setting up Cocos2d-JS to add the Box2D engine to your games
Creating a physics world
Giving the world a realistic gravity
Combining bodies, shapes, and fixtures to create a physics object
Creating a material
Creating static objects
Creating dynamic objects
Attaching sprites to physics objects
Selecting physics objects with the mouse/finger...