Decimal.js
An arbitrary-precision Decimal type for JavaScript
Datejs
Datejs is an open-source JavaScript Date Library.
Inversify Js
A powerful and lightweight inversion of control container for JavaScript & Node.js apps powered by TypeScript.
Underscore String
String manipulation extensions for Underscore.js javascript library.
String.js
Extra JavaScript string methods.
Css3 Finalize
Tired of adding prefix for each broswer when it comes to the new css3 attributes?
Sprintf.js
sprintf.js is a complete open source JavaScript sprintf implementation.
Placeholder Shiv
Tiny polyfill for the placeholder form element attribute. Requires Prototype.js.
Xregexp
Extended JavaScript regular expressions
Hitch
A lightweight engine that allows you to hitch new capabilities to the browser (prollyfill).
Tiny Color
Fast, small color manipulation and conversion for JavaScript
Core Lib
A port of the Ruby 1.9.3 corelib to coffeescript/javascript/node that conforms to rubyspec.org.
Char Funk
a Unicode character utility for JavaScript
Bignumber.js
A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic
Ratio.js
Rational numbers for Javascript
Classing Js
Brings the world of classical OOP to javascript
Typecast.js
Typecast.js :: Solving the simple problems