MongoClient連接回調(diào)不起作用

我正在嘗試學(xué)習(xí)關(guān)于MongoDB的課程，但在運(yùn)行以下代碼時(shí)遇到問(wèn)題，這些代碼應(yīng)該允許我連接到mongoDB。我有兩個(gè)模塊：

mongoConnect.js

import { MongoClient} from 'mongodb';
import {EventEmitter} from 'events';
const uri = "<MYCONNSTRING>";
const dbName = "test";

class MongoConnect extends EventEmitter{
    constructor(){
        super();
        this.mongoClient = new MongoClient(uri,{useUnifiedTopology:true});
    }
    connect() {
        this.mongoClient.connect((err,mongodb)=>{
            if(err) throw err;
            console.log('Connection to DB Established');
            MongoConnect.blogDatabase = mongodb.db(dbName);
            this.emit('dbConnection');
        })
    }
};
export default  MongoConnect;

App.js（主模塊文件）

import express from 'express';
import MongoConnect from './mongoConnect.js';
const port = process.env.PORT || 3000;
const app = express();
const mongoConnect = new MongoConnect();

mongoConnect.on('dbConnection', ()=> {
    app.listen(port, ()=>{
        console.log(`server listening on port: ${port}`);
    });
});
mongoConnect.connect();

問(wèn)題是：connect()方法內(nèi)部的回調(diào)永遠(yuǎn)不會(huì)執(zhí)行。我在控制臺(tái)中看不到消息，也不知道如何繼續(xù)。