Question 200538 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – How to use export insde a function with ES6?

I want to export the client.db() after the connection but the problem is that the default export must be at the top level of a file or module declaration.

this is my code.

import { MongoClient } from "mongodb";
import app from "./app.js";

const client = new MongoClient("connect to mongodb")

async function start() {
    await client.connect()
    export default client.db() 
    app.listen(3000, ()=> {
        console.log("Your server is running at port 3000")
    })

}

I tried to create a global variable and set it equal the client:db() inside the start() function, the export default get the variable as the initial value "undefined".

Tags:

2

Answers


  1. 0

    Default exports should always be at the top level of a file or module declaration and there is no workaround about this.

    However, there is a solution for what are you trying to achieve by using the singleton pattern. You can read more about this pattern on the link below:

    Singleton Pattern

    Your main goal is to be able to export just a single instance of the client db and you want every part of your application to use that same instance.

    You can achieve this by using the below implementation:

    import {
  MongoClient
} from "mongodb";

const client = new MongoClient("connect to mongodb")

let clientDb = null;

async function getClientDb() {

  if (clientDb) return clientDb;

  await client.connect();
  clientDb = client.db();

  return clientDb;
}


export default getClientDb;

    Now in order to use your db instance where you need it, simply import the getClientDb function and use its resolved return value.

    Login or Signup to reply.
  2. 0

    In modules, you can actually use top-level awaits in most situations. Assuming there aren’t any weird cross-dependencies, you can do something like this:

    import { MongoClient } from 'mongodb';
import app from './app.js';

app.listen(3000, () => {
  console.log('Your server is running at port 3000.');
});

const client = new MongoClient('connect to mongodb');    
await client.connect();
export default client.db();
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search