javascript指定排序方式

<pre name="code" class="javascript">    		//測試數據
    	   var data  = [{name:"zhangsan",age:21},{name:"lisi",age:22},{name:"wangwu",age:19}];
		   
		   function createComparisonFunction(propertyName,orderBy_DESC){
		   	   return function (object1,object2){
			   	 var value1 = object1[propertyName];
				 var value2 = object2[propertyName];
				 if(orderBy_DESC){//降序
					if(value1>value2){
						return -1;
					}else if(value1<value2){
						return 1;
					}else{
						return 0;
					}						
				 }else{//默認升序
				 	if(value1<value2){
						return -1;
					}else if(value1>value2){
						return 1;
					}else{
						return 0;
					}
				 }
			   }
		   }
		   //指定排序方式，我這裏是按照名字降序，第二個參數有值則降序，只傳入第一個參數則升序
		   data.sort(createComparisonFunction("name",1))
			//打印結果
		   for(var i = 0 ;i<data.length;i++){
				document.write(data[i].name+"\n\n");
		   }