stylesheet injector

load.js

var load = function(url, callback) {

	if ( ! window.registeredStylesheets ) window.registeredStylesheets = [];

	if ( window.registeredStylesheets.indexOf(url) == -1)
	{
		(document.head || document.getElementsByTagName("head")[0]).appendChild(function(){
		
			var link = document.createElement('link');
		
			link.setAttributes({
				'rel' : 'stylesheet',
				'type' : 'text/css',
				'href' : url
			});
		
			return link;
		
		}());
		
		if ( typeof callback == 'function' ) {
		
			(function checkLoaded() {
			
				for ( var i = 0; i < document.styleSheets.length; i++ ) {
				
					if ( new RegExp(url).test(document.styleSheets[i].href) ) {
					
						callback()
						
						return;
					
					}
					
				}
			
				setTimeout(checkLoaded, 1)
			
			})()
		
		}
		
		window.registeredStylesheets.push(url);
	}
}