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