Sugar
A Javascript library for working with native objects.
Nerdamer
a symbolic math expression evaluator for javascript
Char Funk
a Unicode character utility for JavaScript
Ratio.js
Rational numbers for Javascript
Typecast.js
Typecast.js :: Solving the simple problems
Object.observe
Object.observe polyfill/shim trying to be compliant
Selectivizr
Selectivizr is a JavaScript utility that emulates CSS3 pseudo-classes and attribute selectors in Internet Explorer 6-8.
Poly
Small, fast, awesome. The only ES5-ish set of polyfills (shims) you can mix-and-match because they're individual AMD modules.
Es6 Shim
ECMAScript 6 (Harmony) compatibility shims for legacy JavaScript engines
Placeholders.js
A JavaScript polyfill for the HTML5 placeholder attribute
Core Lib
A port of the Ruby 1.9.3 corelib to coffeescript/javascript/node that conforms to rubyspec.org.
Args.js
Create javascript functions with optional, default, grouped and named parameters.
Big.js
A small, fast JavaScript library for arbitrary-precision decimal arithmetic.
Datejs
Datejs is an open-source JavaScript Date Library.
Length.js
📏 JavaScript library for length units conversion.
Taggd
A tool to show and add tags to images
HTML5shiv
This script is the defacto way to enable use of HTML5 sectioning elements in legacy Internet Explorer.