JS Bin is a webapp specifically designed to help JavaScript and CSS folk test snippets of code, within some context, and debug the code collaboratively.

JS Bin allows you to edit and test JavaScript and HTML. Once you’re happy you can save, and send the URL to a peer for review or help. They can then make further changes saving anew if required. JS Bin was built by Remy Sharp and is completely open source and available on http://github.com/remy/jsbin.

You can also check out JSFiddle, which is a handy online editor for JavaScript too.

Requirements: -
Demo: http://jsbin.com
License: MIT License