js获取url指定得参数值

 function GetqueryString(name){                        var reg = new RegExp("(^|&)"+ name +"=([^&]*)(&|$)");                        var r = window.location.search.substr(1).match(reg);                        if(r!=null)return  unescape(r[2]); return null;                                             }alert(GetqueryString("code")); //123// http://www.abc.com/?code=123