This project is based on an open source Node.js application posted at: http://socket.io/get-started/chat/. Your job is to modify the index.js page so that the app will have two new features:

Whenever someone joins or leaves the room, a message will be displayed to all users.

Instead of having a username, each user is assigned a socket generated session id when he/she first joins.

index.js

var app = require('express')(); var http = require('http').Server(app); var io = require('socket.io')(http); app.get('/', function(req, res){ res.sendFile(__dirname + '/index.html'); }); io.on('connection', function(socket){ socket.on('chat message', function(msg){ io.emit('chat message', msg); }); }); http.listen(3000, function(){ console.log('listening on *:3000'); }); 

You can download this project source code from https://github.com/rauchg/chat-example

When a user joins the chat room, you need to register the connect event. For example:

io.on(connect, function(socket)) {

io.emit(chat message, --- someone just joined the room!!!);

});

When a user leaves the chat room, you need to register the disconnect event on that particular socket. For example:

io.on(connection, function(socket) {

socket.on(disconnect, function() {

io.emit(chat message, --- someone just left the room!!!);

});

});

To get the session Id from each user, you can use socket.client.id property. For example:

io.emit(chat message, --- + socket.client.id + just joined the room!!!);

You only need to submit the modified index.js file.