A simple chat server written in node.js. Implements usernames, some commands. Port 9001.

gistfile1.js

// Simple Node.Js chat server
// My first attempt at a node application. Supports usernames, and a few text-based commands.
// Dave The Software Dev - davethesoftwaredev@gmail.com
// Hope this helps you

var net = require('net');

var connection = function(id, connection, server) {
  this.id = id;
	this.conn = connection;
	this.server = server;
	this.username = '';
	
	var _this = this;
	
	this.conn.on('error', function(e) {
		_this.server.close(_this.id);
	});
		
	this.conn.on('close', function(e) {
		_this.server.close(_this.id);
	});
	
	this.conn.on('data', function(data) {
		var text = data.toString();
		if(_this.username == '' && text.match(/^\/username/)) {
			var user = text.substring(9).trim();
			if(_this.username != '') {
				_this.send('You may not change your username.\n');
			}
			else if(user != '<Anonymous>' && _this.server.doesUserExist(user) == false) {
				_this.username = text.substring(10).trim();
				_this.server.broadcastAll(_this.username + ' has joined the chat.\n');
			}
			else {
				_this.send('That username is not available.\n');
			}
		}
		else if(text.match(/^\/exit/)) {
			_this.server.close(_this.id);
		}
		else if(text.match(/^\/users/)) {
			var users = _this.server.getUserList();

			if(users.length == 0) {
				_this.send('No users exist in chat.\n');
			}
			else {
				for(var i = 0; i < users.length; i++) {
					_this.send(users[i] + '\n');
				}
			}
		}
		else if(_this.username == '') {
			_this.send('Please choose a username by sending /username <name>\n');
		}
		else {
			_this.server.broadcastAll(_this.username + ': ' + text.trim() + '\n');
		}
	});
	
	this.close = function() {
		_this.conn.destroy();
	}
	
	this.send = function(data) {
		_this.conn.write(data);
	}
	
	console.log('New connection from ' + connection.remoteAddress);
	this.send("Welcome to Dave's simple chat server.\n");
	this.send("Commands:\n");
	this.send("	/username <user> - Sets your username.\n");
	this.send("	/users			 - Returns a list of users in the chat.\n");
	this.send("	/exit			 - Leaves the chat.\n");
	this.send("Please set your username prior to sending text.\n");
	this.send("-----------------------------------------------------------\n");
}

var server = function() {
	var _this = this;

	this.broadcastAll = function(data) {
		for(var i = 0; i < this.connections.length; i++) {
			_this.connections[i].send(data);
		}
	}

	this.broadcastAllExcept = function(id, data) {
		for(var i = 0; i < _this.connections.length; i++) {
			if(_this.connections[i].id != id)
				_this.connections[i].send(data);
		}
	}
	
	this.handleConnection = function(conn) {
		var conn = new connection(_this.currentConnectionId++, conn, _this);
		_this.connections.push(conn);
	}
	
	this.start = function(port) {
		_this.server.listen(port);
	}
	
	this.close = function(id) {
		for(var i = 0; i < _this.connections.length; i++) {
			if(_this.connections[i].id == id) {
				if(_this.connections[i].username == '') {
					_this.broadcastAllExcept(id, '<Anonymous> has left the chat.\n');
				}
				else {
					_this.broadcastAllExcept(id, _this.connections[i].username + ' has left the chat.\n');				
				}
				
				_this.connections[i].close();
				_this.connections.splice(i, 1);
				break;
			}
		}
	}
	
	this.getUserList = function() {
		var users = [];
		
		for(var i = 0; i < _this.connections.length; i++) {
			if(_this.connections[i].username == '') {
				users.push('<Anonymous>');
			}
			else {
				users.push(_this.connections[i].username);
			}
		}
		
		return users;
	}
	
	this.doesUserExist = function(username) {
		for(var i = 0; i < _this.connections.length; i++) {
			if(_this.connections[i].username == username) {
				return true;
			}
		}
		
		return false;
	}
	
	this.server = net.createServer(this.handleConnection);
	this.currentConnectionId = 0;
	this.connections = [];
}

var mainServer = new server();
mainServer.start(9001);