Paper.js
The Swiss Army Knife of Vector Graphics Scripting – Scriptographer ported to JavaScript and the browser, using HTML5 Canvas. Created by @juerglehni & @jonathanpuckey
Joint
JavaScript diagramming library
Jcrop
Jcrop (official) - Image Cropping Plugin for jQuery
Processing.js
A port of the Processing visualization language to JavaScript.
Raphael
JavaScript Vector Library
jQuery QR Code
qrcode generation standalone (doesn't depend on external services)
Svg.js
A lightweight library for manipulating and animating SVG
Bonsai
BonsaiJS is a graphics library and renderer
jQuery Focuspoint
jQuery plugin for 'responsive cropping'. Dynamically crop images to fill available space without cutting out the image's subject. Great for full-screen images.
Snap.svg
The JavaScript library for modern SVG graphics.
Croppie
A Javascript Image Cropper
Clmtrackr
Javascript library for precise tracking of facial features via Constrained Local Models
Proton
A particle engine for html5
Graphicsjs
A lightweight JavaScript graphics library with the intuitive API, based on SVG/VML technology.
Obelisk.js
JavaScript Engine for Building Isometric Pixel Element with HTML5 Canvas
Canvg
Javascript SVG parser and renderer on Canvas
Image Mapster
jQuery plugin for enhancing HTML Image maps