动态加载css和java script

var portalLoader = {
	dojo : {
		url:"/Dojo/dojo-release-1.6.1/"
	},
	call : (function() {
		function hasFile(tag, url) {
			var contains = false;
			var files = document.getElementsByTagName(tag);
			var type = tag == "script" ? "src" : "href";
			for ( var i = 0, len = files.length; i < len; i++) {
				if (files[i].getAttribute(type) == url) {
					contains = true;
					break;
				}
			}
			return contains;
		}

		function fileExt(url) {
			var att = url.split('.');
			var ext = att[att.length - 1].toLowerCase();
			return ext;
		}

		function loadFile(element, callback, parent) {
			var p = parent && parent != undefined ? parent : "head";
			var h = document.getElementsByTagName(p)[0];
			h.appendChild(element);
			if (callback) {
				callback();
			}
		}
		
		function loadCssFile(files, callback) {
			var urls = files && typeof (files) == "string" ? [ files ] : files;
			for ( var i = 0, len = urls.length; i < len; i++) {
				var cssFile = document.createElement("link");
				cssFile.setAttribute('type', 'text/css');
				cssFile.setAttribute('rel', 'stylesheet');
				var filePath = portalLoader.dojo.url + urls[i];
				cssFile.setAttribute('href', filePath);
				if (!hasFile("link", filePath)) {
					loadFile(cssFile, callback);
				}
			}
		}		

		function loadScript(files, callback, parent) {
			var urls = files && typeof (files) == "string" ? [ files ] : files;
			for ( var i = 0, len = urls.length; i < len; i++) {
				var script = document.createElement("script");
				script.setAttribute('type', 'text/javascript');
				var filePath = portalLoader.dojo.url + urls[i];
				script.setAttribute('src', filePath);
				if (!hasFile("script", filePath)) {
					loadFile(script, callback, parent);
				}
			}
		}		

		function toArray(obj) {
			if (obj.length == null)
				return new Array(obj);
			else
				return obj;
		}

		function tryToArray(obj) {
			try {
				return toArray(obj);
			} catch (e) {
				try {
					return obj.split(",");
				} catch (e) {
					return obj;
				}
			}
		}
		
		function includeFile(options) {
			if (options) {
				var cssFiles = tryToArray(options.css);
				var scriptFiles = tryToArray(options.script);

				loadCssFile(cssFiles, function() {
					//loadScript(scriptFiles, null, "body");
					loadScript(scriptFiles);
				});
			}
		}
		
		return {
			require : includeFile
		};
	})()
};

var require = function(options) {
	portalLoader.call.require(options);
};

 

<script type="text/javascript" src="js/portalLoader.js"></script>

<script type="text/javascript">
	require({         
		css:["dojo/resources/dojo.css","dijit/themes/tundra/tundra.css"],        
		script:["dojo/dojo.js"]    
	});
</script>