Paper.js - Open source vector graphics scripting framework that runs on top of the HTML5 Canvas.
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.
p5.js - JS library for creating graphic and interactive experiences
Konva - Konva is 2d Canvas JavaScript framework for drawings shapes, animations, node nesting, layering, filtering, event handling, drag and drop and much more.
Three.js - A JavaScript 3D library which makes WebGL simpler.
Pixi.js - Fast lightweight 2D library that works across all devices