js获取参数

   function getQueryString(name) {
            var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
            var r = window.location.search.substr(1).match(reg);
            if (r != null) return unescape(r[2]); return null;
        }

        var paymenttype = GetQueryString("paymenttype");