Simple backend to read contacts from a mongodb DB

index.js

require('dotenv').config()
import { MongoClient } from 'mongodb'

const connectMongoDB = () => MongoClient.connect(process.env.MONGODB)

const getContacts = (req, res) => {
  return connectMongoDB()
    .then(
      db => db.collection('contacts')
        .find({})
        .toArray()
        .then(documents => ({db, documents}))
    )
    .then(({db, documents}) => {
      db.close()
      return documents
    })
    .then(contacts => res.json(contacts))
    .catch(err => res.status(400).send(err.toString()))
}

export const handler = getContacts