Guid generator in Javascript.

gistfile1.js

(function(){
       if(!window.String.UUID){
		var matcher = /[xy]/g;
		var replacer = function(c) {
			var r = Math.random()*16|0;
			var v = c == 'x' ? r : (r&0x3|0x8);
			return v.toString(16);
		};
		//maybe shouldn't be modifying the global variable, but seems like the best place to put this.
		window.String.UUID = function(){
			//see http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript for more details.
			return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(matcher, replacer);
		};
	}
})();