monogdb 3.X更新之后這么寫為什么不對了？

const mongodb = require('mongodb')  //npm 

const mongoClient = mongodb.MongoClient

const url = 'mongodb://127.0.0.1:27017/shafa'

mongoClient.connect(url, function (err, db) {
    if (err) throw err
    
    const obj = db.collection('users')  //先找到操作哪個集合

    var data = {name:'小小明',age:18}

    obj.insert(data, function (err, result) {

        console.log(result)
        // result()
    })
})