Connect to MongoDB using promise

MongoDBConnect.js

const mongodb = require('mongodb');
const MongoClient = mongodb.MongoClient;
const config = require('../config/config');
const mongoUrl = config.MONGO_URL

exports.connectToDb = function () {
    return new Promise((resolve, reject) => {
        MongoClient.connect(mongoUrl, {
            useNewUrlParser: true
        }, function (err, db) {
            if (err) {
                reject(err);
                return;
            }
            resolve(db);
        });
    });
}