matter.js
Matter.js is a 2D rigid body physics engine for the web. It supports compound bodies, concave and convex hulls, physical properties, restitution, collisions, stable stacking, friction and resistance, constraints, sleeping bodies, etc.
Code Libraries: Physics
p2.js
The p2.js library is a 2D rigid body physics engine written in JavaScript. It includes collision detection, friction, restitution, motors, springs, advanced constraints and various shape types.
Coffee-Physics
A lightweight physics engine, written in CoffeeScript. It works with the canvas, the DOM and WebGL.
Chipmunk-js
Chipmunk-js is a port of the Chipmunk Physics library to JavaScript. Chipmunk-js is a simple, lightweight, fast and portable 2D rigid body physics.
box2dweb
box2dweb is a physics engine ported from Box2dFlash which, itself, was a port of the original Box2D.
PhysicsJS
A modular, extendable, and easy-to-use physics engine for JavaScript. The simulation engine works with any type of visual representation: DOM, canvas, etc.