Sugar is a Javascript library that extends native objects with helpful methods. It is designed to be intuitive, unobtrusive, and let you do more with less code.
It brings lots of new featured for working with strings, numbers, dates, arrays, objects,regular expressions and functions.

Sugar Features:
- extends native Javascript objects with helpful, intuitive methods.
- adds cross browser functionality when it is broken or missing.
- is entirely test driven from the ground up and includes a massive suite of tests.
- layers in methods when necessary, but defers to native implementations when available.
- enhances Javascript dates and can parse and output a variety of languages.
- plays nicely with other Javascript frameworks and third-party code.
- is simple to understand and easy to use.
- is fully ECMAScript compliant.
As an example:
Object.fromQueryString Converts the query string of a URL into an object.
capitalize would make the 1st letter capital
isEven and isOdd helps finding if the given number is odd or even
count would find how many times the given character exists in an array
isFuture would return if any given date is bigger than today
- and so much more.
The library is very well-documented with powerful API and it is a huge helper for JavaScript-heavy applications.
Compatibility: All Major Browsers
Website: http://sugarjs.com/