[node.js] What is an example of the simplest possible Socket.io example?

So, I have been trying to understand Socket.io lately, but I am not a supergreat programmer, and almost every example I can find on the web (believe me I have looked for hours and hours), has extra stuff that complicates things. A lot of the examples do a bunch of things that confuse me, or connect to some weird database, or use coffeescript or tons of JS libraries that clutter things up.

I'd love to see a basic, functioning example where the server just sends a message to the client every 10 seconds, saying what time it is, and the client writes that data to the page or throws up an alert, something very simple. Then I can figure things out from there, add stuff I need like db connections, etc. And yes I have checked the examples on the socket.io site and they don't work for me, and I don't understand what they do.

This question is related to node.js socket.io

The answer is

Edit: I feel it's better for anyone to consult the excellent chat example on the Socket.IO getting started page. The API has been quite simplified since I provided this answer. That being said, here is the original answer updated small-small for the newer API.

Just because I feel nice today:


<!doctype html>
        <script src='/socket.io/socket.io.js'></script>
            var socket = io();

            socket.on('welcome', function(data) {

                // Respond with a message including this clients' id sent from the server
                socket.emit('i am client', {data: 'foo!', id: data.id});
            socket.on('time', function(data) {
            socket.on('error', console.error.bind(console));
            socket.on('message', console.log.bind(console));

            function addMessage(message) {
                var text = document.createTextNode(message),
                    el = document.createElement('li'),
                    messages = document.getElementById('messages');

        <ul id='messages'></ul>


var http = require('http'),
    fs = require('fs'),
    // NEVER use a Sync function except at start-up!
    index = fs.readFileSync(__dirname + '/index.html');

// Send index.html to all requests
var app = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/html'});

// Socket.io server listens to our app
var io = require('socket.io').listen(app);

// Send current time to all connected clients
function sendTime() {
    io.emit('time', { time: new Date().toJSON() });

// Send current time every 10 secs
setInterval(sendTime, 10000);

// Emit welcome message on connection
io.on('connection', function(socket) {
    // Use socket to communicate with this particular client only, sending it it's own id
    socket.emit('welcome', { message: 'Welcome!', id: socket.id });

    socket.on('i am client', console.log);


Similar questions with node.js tag:

Similar questions with socket.io tag: