server.js

// require('dotenv').config();
const express = require('express');
const path = require('path');
const http = require('http');
const socketIO = require('socket.io');

const app = express();
const server = http.createServer(app);
const io = socketIO(server);

server.listen(3000);

console.log( __dirname );

app.use(express.static(path.join(__dirname ,'public'))) ;

let connectedUsers = [];

io.on('connection', (socket) => {

    console.log("conexão detectada...");    

    socket.on('join-request', (username) => {

        console.log('usuário enviou o nome: ', username);

        socket.username = username;
        connectedUsers.push(username);
        console.log(connectedUsers);

        socket.emit('user-ok', connectedUsers); 

        socket.broadcast.emit('list-update', {
            joined : username,
            list: connectedUsers
        });

    });

    socket.on('disconnect', () => {

        connectedUsers = connectedUsers.filter( u => u != socket.username );
        console.log(connectedUsers);

        socket.broadcast.emit('list-update', {
            left : socket.username,
            list: connectedUsers
        });

    });    

    socket.on('send-msg', (txt) => {

        let obj = {
            username: socket.username,
            message: txt
        };

        // socket.emit('show-msg', obj); 

        socket.broadcast.emit('show-msg', obj);

    });

});