Whatsapp_Web_Node_Server/main.js

const { Client } = require('whatsapp-web.js');
const qrcode = require('qrcode-terminal');
const express = require('express');
const app = express();
app.use(express.json());

const wwebVersion = '2.2407.3';

// Create a new client instance
const client = new Client( 
    {webVersionCache: {
        type: 'remote',
        remotePath: `https://raw.githubusercontent.com/wppconnect-team/wa-version/main/html/${wwebVersion}.html`
    }
});

client.on('ready', () => {
    console.log('Client is ready!');
});

client.on('qr', qr => {
    qrcode.generate(qr, {small: true});
});

// Listening to all incoming messages
client.on('message_create', message => {
    console.log(message.body);
});

function sendMessage(number, message) {
    client.sendMessage(number, message);
}

app.post('/send-message', (req, res) => {
    /*
    This function only accepts numbers formatted as: [CountryCode][Number]@c.us // Example: 39333555887@c.us
    */
    const { number, message } = req.body;
    if (!number || !message) {
        return res.status(400).send('Number and message are required');
    }

    sendMessage(number, message);
    res.send('Message sent');
});

const port = process.env.PORT || 3000;
app.listen(port, () => console.log(`Server running on port ${port}`));

client.initialize();