Paper.js
The Swiss Army Knife of Vector Graphics Scripting – Scriptographer ported to JavaScript and the browser, using HTML5 Canvas.
Code Libraries
mo.js
mo.js is a motion graphics toolbelt for the web.
Anime.js
Anime (/ˈæn.ə.meɪ/) is a lightweight animation library that works with any CSS Properties, individual CSS transforms, SVG or any DOM attributes, and JavaScript Objects.
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.
Phidgets
Phidgets are a line of USB sensors and actuators. They can be controlled from the browser or Node using JavaScript.
annyang
A tiny speech recognition library that lets your users control your site with voice commands. It has no dependencies, weighs just 2 KB, and is free to use and modify.
AR.js
AR.js is an efficient augmented reality library based on THREE.js and jsartoolkit5. It works on any phone with WebGL and WebRTC.
WebGazer.js
WebGazer.js is an eye tracking library that uses common webcams to infer the eye-gaze locations of web visitors on a page in real time. The eye tracking model it contains self-calibrates by watching web visitors interact with the web page and trains a mapping between the features of the eye and positions on the screen.
Songbird
Songbird is a real-time spatial audio encoding library for WebAudio applications. It allows web developers to dynamically spatially-encode streaming audio content into ambisonics signal, which is rendered using Omnitone to output stereo sound, for realistic 3D audio.
Primrose VR
The Primrose Framework helps web developers create virtual reality experiences within standard web browsers, on desktop and mobile devices alike, using the free, open source web development tools with which they are most familiar.