JS "trycatch工厂模式"

大家都用过Ajax的异步交互，下面的代码中使用  "trycatch工厂模式"  来进行针对Ajax请求对象的变化点进行封装

<script type="text/javascript">

	var createHttpRequest = function() {

		var GetHttpRequest = [

			function() {return new ActiveXObject("Microsoft.XMLHTTP");},

			function() {return new XMLHttpRequest();}

		];

		for(var ele in GetHttpRequest) {

			try {

				GetHttpRequest[ele]();

			} catch {

				continue;

			}

			this.createHttpRequest = GetHttpRequest[ele]();

			return GetHttpRequest[ele]();

		}

　　　　　 throw new Error("这些对象都不能用！");

	}

  </script>