Node.Js同步mongdb数据

/** 
 * @desc 同步数据
 */
router.post("/user/copy", (req, res) => {
  const query = User.find({});
  let pageSize = 2; //查询数量
  let pageCount = 1; //查询页码
  let insertFlag = true; //是否添加数据

  let setTime = setInterval(() => {
    let startPage = (pageCount - 1) * pageSize; //开始条数
    query.limit(pageSize); //设置查询条数
    query.skip(startPage); //开始条数
    console.log("pageSize", pageSize, "startPage", startPage, "pageCount", pageCount)
    pageCount += 1;
    query.exec((err, data) => {
      if (err) throw err;
      if (data.length < pageSize) {
        console.log(‘close‘);
        clearInterval(setTime);
      }
      for (var i = 0; i < data.length; i++) {
        const userData = new UserData({
          _id: data[i]._id,
          name: data[i].name,
          password: data[i].password,
          type: data[i].type,
          avatar: data[i].avatar,
          date: data[i].date
        });
        //去除重复数据
        UserData.findOne({
            _id: objectId(data[i]._id)
          },
          function (err, doc) {
            if (err) throw err;
            if (doc != null) {
              insertFlag = false;
            }
          }
        );
        if (insertFlag) {
          userData
            .save()
            .then(userData => res.json(userData))
            .catch(err => console.log(err));
        }
      }
    });
  }, 1000)

});