Alasql
AlaSQL.js - JavaScript SQL database for browser and Node.js. Handles both traditional relational tables and nested JSON data (NoSQL). Export, store, and import data from localStorage, IndexedDB, or Excel.
Punycode.js
A robust Punycode converter that fully complies to RFC 3492 and RFC 5891, and works on nearly all JavaScript platforms.
Canvas Xpress
JavaScript VisualizationTools
Local Storage
A localStorage polyfill
Accounting.js
A lightweight JavaScript library for number, money and currency formatting - fully localisable, zero dependencies.
Power Array
Boosted Performance Array
Money.js
money.js is a tiny (1kb) javascript currency conversion library, for web & nodeJS
Z.js
turns content (in)visible
jQuery JSONP
jquery jsonp plugin
Easy Pie Chart
Lightweight jQuery plugin to render simple, animated and retina ready pie charts with the HTML5 canvas element
D3 Cloud
Create word clouds in JavaScript.
Jumly
Rendering engine for UML diagrams in JavaScript
Isjs
Check your data against regular expressions or known keywords.
Dc.js
Multi-Dimensional charting built to work natively with crossfilter rendered with d3.js
Uv Charts
Simple yet powerful JavaScript Charting library built using d3.js
Rusha
High-performance pure-javascript SHA1 implementation suitable for large binary data, reaching up to half the native speed.
Backgrid
Finally, an easily stylable semantic HTML data grid widget with a Javascript API that doesn't suck.