Building a Chat Server

In a world that’s increasingly real-time, what is more real-time than chat? So where should we begin? Let’s start with a TCP-based chat server we can connect to with Telnet. Not only is it a simple place to start, but it’s also something we can write 100% in Node.

The first thing we need to do is include the TCP libraries from Node and create a new TCP server (see Example 2-1).

var net = require('net')

var chatServer = net.createServer()

chatServer.on('connection', function(client) {
  client.write('Hi!\n');
  client.write('Bye!\n');

  client.end()
})

chatServer.listen(9000)

First, we include the net module. This contains all the TCP stuff for Node. From that, we can create a TCP server by calling the net.createServer() method. Now that we have a server, we want it to do stuff. So we add an event listener by using the on() method. Whenever the connection event happens, the event listener will call the function we gave it. A connection event happens when a new client connects to the server.