如何获取url里面的参数

function UrlSearch() {
          var name, value;
          var str = location.href; //取得整个地址栏
          var num = str.indexOf("?")
          str = str.substr(num + 1); //取得所有参数   stringvar.substr(start [, length ]

          var arr = str.split("&"); //各个参数放到数组里
          for(var i = 0; i < arr.length; i++) {
            num = arr[i].indexOf("=");
            if(num > 0) {
              name = arr[i].substring(0, num);
              value = arr[i].substr(num + 1);
              this[name] = value;
            }
          }
        }
        var Request = new UrlSearch();