Xdate
A Modern JavaScript Date Library
Timezone Js
Timezone-enabled JavaScript Date object. Uses Olson zoneinfo files for timezone data.
Placeholders.js
A JavaScript polyfill for the HTML5 placeholder attribute
HTML5shiv
This script is the defacto way to enable use of HTML5 sectioning elements in legacy Internet Explorer.
Poly
Small, fast, awesome. The only ES5-ish set of polyfills (shims) you can mix-and-match because they're individual AMD modules.
Stringformatter
JS string formatter that supports objects, currency, date/time, decimals, and more supports easy extension and garbage collection ... goes far beyond sprintf approach.
Numeral
A javascript library for formatting and manipulating numbers.
Flexie
Legacy support for the CSS3 Flexible Box Model
Console.message
Console messages for cool kids
Selectivizr
Selectivizr is a JavaScript utility that emulates CSS3 pseudo-classes and attribute selectors in Internet Explorer 6-8.
Store
A better way to use localStorage and sessionStorage
Sugar
A Javascript library for working with native objects.
ES5 Shims
ECMAScript 5 compatibility shims for legacy JavaScript engines
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**).
Angled Edges
:triangular_ruler: Quickly create angled section edges using only Sass
Respond
A fast & lightweight polyfill for min/max-width CSS3 Media Queries (for IE 6-8, and more)
jQuery Number
Easily format numbers for display use. Replace numbers inline in a document, or return a formatted number for other uses.