递归--给每一项新增属性

   

 format(arr) {
      arr.forEach((el) => {
        if (el.children && el.children.length > 0) {
          el.value = el.id;
          el.label = el.orgName;
          this.format(el.children);
        } else {
          el.value = el.id;
          el.label = el.orgName;
        }
      });
      return arr;
    },