Paper.js - Open source vector graphics scripting framework that runs on top of the HTML5 Canvas.
altcanvas - Altcanvas is a project for developing a new and more intuitive GUI framework for handheld devices.
p5.js - JS library for creating graphic and interactive experiences
Three.js - A JavaScript 3D library which makes WebGL simpler.
GoJS - GoJS is a JavaScript library for building interactive diagrams on HTML web pages. Build apps with flowcharts, org charts, BPMN, UML, modeling, and other visual graph types.
Snap.svg - Snap.svg is a javascript SVG library for the modern web.