记录---随机生成字符串的方法

 guid() {
      return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(
        /[xy]/g,
        function (c) {
          var r = (Math.random() * 16) | 0,
            v = c == "x" ? r : (r & 0x3) | 0x8;
          return v.toString(16);
        }
      );
    },