Enquire.js

Enquire.js is an awesome little Javascript library for responsive web design.

I have been increasingly using Enquire.js recently in projects. It allows you simply and easily to match the media queries in you CSS with Javascript callbacks. This is a very clean way to perform any javascript functions which are needed based on the matching or un-matching of media queries.

This is much more efficient and cleaner way to handle responsive Javascript than using techniques such as adding multiple resize functions to the browser window.

Check out the project page on GitHub.