a small TCP-based chat room server application with Node.js

tcp-server.js

// including the net module
const net = require('net');

// clients array
let clients = [];

// a nice little logger with a time stamp
// loggin messages for both server and Client
function logger(m){
  let d = new Date().toLocaleString();
  let t = `${d} - ${m.toString()}\n`;
  console.log(t);
  return t;
}

// how many alive ?
const alive = () => `Server: ${clients.length} member(s) currently online`;

// the server sends greeting for each new user
function serverGreet(cli){
  cli.write(logger('Server: Welcome'));
  cli.write(logger(alive()));
  cli.write(logger('Server: Say Hello to everyone :)'));
  cli.write(logger('Hit Ctrl + C to exit'));
  cli.write(' ----- MrGhost TCP RoOm-------- \n\n');
}

// broadcasting messages to all users
function broadcast(msg){
  clients.map(c => {
    c.write(logger(msg));
  });
}

// sending messages to all, but yourself
// if you're online alone, log your messages to the server
// of course I wanna see everything in my TCP chat room :)
function send2All(id, msg){
  clients.map(c => {
    if(c.id !== id){
      c.write(logger(`Client ${id}: ${msg}`));
    } else if(clients.length === 1) {
      logger(`Client ${id}: ${msg}`);
    }
  });
}

// add a client to the list and broadcast it
function addCli(cli){
  clients.push(cli);
  broadcast(`Server: Client ${cli.id} Joined.`);
}

// removes a client and broadcast it
// if no one's online, log it to the server
function remCli(cli){
  clients.splice(clients.indexOf(cli), 1);

  if(clients.length){
    broadcast(`Server: Client ${cli.id} left.`);
    broadcast(alive());
  } else {
    logger(`Client ${cli.id} Left.`);
    logger(alive());
  }
}

// creating the TCP Server
const tcpServer = net.createServer(cli => {
  // giving a unique ID to each User
  // notice how I didn't simply used cli.id = client.length + 1
  // because this method will cause duplicate IDs when the first users leave. see below
  // client number 1 joins, id is 1
  // client number 2 joins, id is 2
  // client number 1 leaves, so client.length will equal 1 again
  // client number 3 joins, but the id will be resolved as 2 because id = client.length + 1
  // so we will have two clients with the same id!!
  // the method below tries to find the last element in the array and get the id from that element
  // if there is a 'last child' it will take his Id and increment it by 1
  // if there isn't anything, we will have our first user with the ID of 1
  cli.id = clients[clients.length - 1].id ? clients[clients.length - 1].id + 1 : 1

  // adding the new client
  addCli(cli);

  // sending the greetings messages by server
  serverGreet(cli);

  // listening for any type of data and send it to all
  // see send2All() on line 38
  cli.on('data', data => send2All(cli.id, data.toString() ) );

  // if the connection from the client closes, remove the client from the clients list
  cli.on('close', () => remCli(cli));

});

// listening for Errors
tcpServer.on('error', err => {
  throw err;
});

// starting the TCP Server
tcpServer.listen(3000, () => {
  console.log('TCP Server started on port 3000');
});