Paper.js - Open source vector graphics scripting framework that runs on top of the HTML5 Canvas.
Pixi.js - Fast lightweight 2D library that works across all devices
p5.js - JS library for creating graphic and interactive experiences
Snap.svg - Snap.svg is a javascript SVG library for the modern web.
Three.js - A JavaScript 3D library which makes WebGL simpler.
Raphael - Raphael.js is an Object Oriented drawing library. It is good at making in-depth diagrams with complex interactions.