Advanced Node and Express - Announce New Users

client.js

$(document).ready(function () {
  /* Global io */
  let socket = io();

  socket.on('user', (data) => {
    $('#num-users').text(data.currentUsers + ' users online');
    let message = data.username + (data.connected ? ' has joined the chat.' : ' has left the chat.');
    $('#messages').append($('<li>').html('<b>' + message + '</b>'));
  });

  // Form submittion with new message in field with id 'm'
  $('form').submit(function () {
    let messageToSend = $('#m').val();
    // Send message to server here?
    $('#m').val('');
    return false; // Prevent form submit from refreshing page
  });
});

server.js

'use strict';
require('dotenv').config();
const express = require('express');
const myDB = require('./connection');
const fccTesting = require('./freeCodeCamp/fcctesting.js');
const session = require('express-session');
const passport = require('passport');
const routes = require('./routes.js');
const auth = require('./auth.js');

const app = express();

const http = require('http').createServer(app);
const io = require('socket.io')(http);
const passportSocketIo = require('passport.socketio');
const cookieParser = require('cookie-parser');
const MongoStore = require('connect-mongo')(session);
const URI = process.env.MONGO_URI;
const store = new MongoStore({ url: URI });

app.set('view engine', 'pug');
app.set('views', './views/pug');

app.use(session({
  secret: process.env.SESSION_SECRET,
  resave: true,
  saveUninitialized: true,
  cookie: { secure: false },
  key: 'express.sid',
  store: store
}));

app.use(passport.initialize());
app.use(passport.session());

fccTesting(app); // For fCC testing purposes
app.use('/public', express.static(process.cwd() + '/public'));
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

io.use(
  passportSocketIo.authorize({
    cookieParser: cookieParser,
    key: 'express.sid',
    secret: process.env.SESSION_SECRET,
    store: store,
    success: onAuthorizeSuccess,
    fail: onAuthorizeFail
  })
);

myDB(async client => {
  const myDataBase = await client.db('database').collection('users');

  routes(app, myDataBase);
  auth(app, myDataBase);

  let currentUsers = 0;
  io.on('connection', (socket) => {
    ++currentUsers;
    io.emit('user', {
      username: socket.request.user.username,
      currentUsers,
      connected: true
    });
    console.log('A user has connected');
    socket.on('disconnect', () => {
      console.log('A user has disconnected');
      --currentUsers;
      io.emit('user', {
        username: socket.request.user.username,
        currentUsers,
        connected: false
      });
    });
  });
  
}).catch(e => {
  app.route('/').get((req, res) => {
    res.render('index', { title: e, message: 'Unable to connect to database' });
  });
});

function onAuthorizeSuccess(data, accept) {
  console.log('successful connection to socket.io');

  accept(null, true);
}

function onAuthorizeFail(data, message, error, accept) {
  if (error) throw new Error(message);
  console.log('failed connection to socket.io:', message);
  accept(null, false);
}
  
const PORT = process.env.PORT || 3000;
http.listen(PORT, () => {
  console.log(`Listening on port ${PORT}`);
});