var Asset = {
    getHead:function(){
    	return document.getElementsByTagName('HEAD').item(0);
    },
	script: function(source){
		var oScript= document.createElement("script"); 
		oScript.type = "text/javascript";
		oScript.src=source;
		return this.getHead().appendChild(oScript);
	},

	css: function(source){
		var _css= document.createElement("link"); 
		_css.type = "text/css";
		_css.rel = "stylesheet";
		_css.media="screen";
		_css.href=source;
		return this.getHead().appendChild(_css);
	},

	image: function(source, onloaded){
		var img = new Image(); 
    	img.src = source;
  		if(onloaded)
		{
			if (img.complete) { 
				onloaded(img);
				return; 
			}
			img.onload = function () { 
				onloaded(img);
			};
		}
	},

	images: function(sources, onloaded,onProgress){
		count = 0;
		var len = sources.length;
		_callback = function(img)
		{
			count++;
			onProgress(img,Math.floor(count/len*100));
			if(count>=len)
			{
				onloaded();
			}
		};
		
		for(var i=0;i<len;i++)
		{
			this.image(sources[i],_callback);
		}
	}
};