RequireJS

RequireJS is a JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, like Rhino and Node. Using a modular script loader like RequireJS will improve the speed and quality of your code.

IE 6+ ………. compatible ✔

Firefox 2+ ….. compatible ✔

Safari 3.2+ …. compatible ✔

Chrome 3+ …… compatible ✔

Opera 10+ …… compatible ✔

Official requirejs.org