Connecting

After configuring the socket, comes connecting to WhatsApp servers.

There are 2 methods to pair your device, the QR code pairing method and the phone number/pairing code method.

After creating the socket, it will automatically connect and then start sending events.

The main event we should be concerned of at the moment is the connection.update event. When listening onto this event, you receive various connection states and a QR string.

For example, utilising the qrcode package:

// you can use this package to export a base64 image or a canvas element.
import QRCode from 'qrcode'

sock.ev.on('connection.update', async (update) => {
  const {connection, lastDisconnect, qr } = update
  // on a qr event, the connection and lastDisconnect fields will be empty

  // In prod, send this string to your frontend then generate the QR there
  if (qr) {
    // as an example, this prints the qr code to the terminal
    console.log(await QRCode.toString(qr, {type:'terminal'})
  }
})

After scanning the code, WhatsApp will forcibly disconnect you, forcing a reconnect such that we can present the authentication credentials. Don't worry, this is not an error. You must handle this as well in the connnection.update event:

import {DisconnectReason} from 'baileys'
sock.ev.on('connection.update', (update) => {
  const {connection, lastDisconnect} = update
  if (connection === 'close' && (lastDisconnect?.error as Boom)?.output?.statusCode === DisconnectReason.restartRequired) {
    // create a new socket, this socket is now useless
  }
})

Auth state

In order to reconnect successfully, we must pass a way for Baileys to persist credentials and encryption keys.

warning

DONT EVER USE THE useMultiFileAuthState IN PROD. YOU HAVE BEEN WARNED. This function consumes a lot of IO. Only use its implementation as a guide. As I said earlier here

After obtaining the relevant creds from WhatsApp, Baileys will drop the creds.update event to make sure you save them. This event triggers every time creds are updated.

// DO NOT USE IN PROD!!!!
const { state, saveCreds } = await useMultiFileAuthState("auth_info_baileys");
// will use the given state to connect
// so if valid credentials are available -- it'll connect without QR
const sock = makeWASocket({ auth: state });
// this will be called as soon as the credentials are updated
sock.ev.on("creds.update", saveCreds);

Pairing Code login

When you want to request a pairing code, you should wait at least until the connecting/QR event like above. You shouldn't worry about the QR events, they just exist there.

The phone number MUST be in E.164 format without a plus sign (+1 (234) 567-8901 -> 12345678901).

sock.ev.on('connection.update', async (update) => {
  const {connection, lastDisconnect, qr } = update
  if (connection == "connecting" || !!qr) { // your choice
    const code = await sock.requestPairingCode(phoneNumber)
    // send the pairing code somewhere
  }
})

Great! You should be connected now.