Decimal.js
An arbitrary-precision Decimal type for JavaScript
Tiny Color
Fast, small color manipulation and conversion for JavaScript
Auto Numeric
autoNumeric is a jQuery plugin that automatically formats currency (money) and numbers as you type on form inputs. It supports most International numeric formats and currency signs including those used in Europe, North and South America, Asia and India (lakhs**).
Mathjs
An extensive math library for JavaScript and Node.js
Sprintf.js
sprintf.js is a complete open source JavaScript sprintf implementation.
Typecast.js
Typecast.js :: Solving the simple problems
Numeral
A javascript library for formatting and manipulating numbers.
Ratio.js
Rational numbers for Javascript
Object.observe
Object.observe polyfill/shim trying to be compliant
Nerdamer
a symbolic math expression evaluator for javascript
Args.js
Create javascript functions with optional, default, grouped and named parameters.
Core Lib
A port of the Ruby 1.9.3 corelib to coffeescript/javascript/node that conforms to rubyspec.org.
Extract Values
A simple helper to extract values from a string based on a pattern.
Datejs
Datejs is an open-source JavaScript Date Library.
Bignumber.js
A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic
Xregexp
Extended JavaScript regular expressions
Char Funk
a Unicode character utility for JavaScript