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Asked: 2026-06-02T08:26:05+00:00

I’ve been staring at node.js and socket.io examples all afternoon and i’m trying to

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I’ve been staring at node.js and socket.io examples all afternoon and i’m trying to piece together a simple page that will tell me how many users I have connected to the server.

I have read the documentation at http://socket.io/ as well as a few tutorials / questions here that outline exactly what i’m trying to do. I have also found create simple node js server and client which does not help me.

Version Information:

node.js – 0.6.15
express – 3.0.0alpha1
socket.io – 0.9.5 (socket.io-client is the same version, however does not find the resource… see comments)
ejs – 0.7.1

Here is my server code:

var express = require('express'),
    config = {
        port: 4000,
        hostname: 'localhost'
    };

var server = module.exports = express.createServer();
    /* server configuration */
    server.use(express.cookieParser('keyboard unicorn'));
    server.use(express.bodyParser());
    server.use(express.methodOverride());
    server.use(express.session({ secret: 'keyboard unicorn' }));
    server.engine('.html', require('ejs').__express);
    server.set('views', __dirname + '/lib/views');
    server.set('view options', { layout: false });
    server.set('view engine', 'html');
    server.use(server.router);
    server.use('/', express.static(__dirname + '/lib/assets'));

var io = require('socket.io').listen(server);

var connections = { 'length': 0 };

io.sockets.on('connection', function(socket) {
    socket.__fd = socket.fd;
    connections[socket.__fd]=socket.remoteAddress;
    ++connections.length;
    console.log('user connected! There are a total of ' + connections.length + ' users online.');
    return socket.on('disconnect',function(){
        delete conns[socket.__fd];
        --connections.length;
        console.log('user disconnected! There are a total of ' + connections.length + ' users remaining online.');
    });
});

server.get('/', function( req, res ) {
    res.render('index', {
        'page_title': 'sample application',
        'number_of_connections': connections.length
    });
});

server.listen(config.port, config.hostname);

Here is my client code: 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title><%= page_title %></title>
</head>
<body>
<div>There is a total of <%= number_of_connections %> user(s) connected.</div>
<script src="http://cdn.socket.io/stable/socket.io.js"></script>
<script type="text/javascript">
var socket = new io.Socket('localhost',{'port':4000});
socket.connect();
socket.on('connect', function() {
    console.log('connected');
});
</script>
</body>
</html>

Here is what is happening when I run the server, and connect with the client.

$ node server.js
   info  - socket.io started

then when I navigate to localhost:4000 on my web browser I get the page with ‘0’ (number_of_connections). Also, I see nothing in the terminal for the server (the on.(‘connection’ is never hit).

On the client, after a second or two, I start to get a massive number of errors (if I leave the console open for a few seconds it crashes the page) see image below:

enter image description here

Please, any help with where to start for debugging this would be appreciated! I just want to get this basic example up and running so I can start playing with / understanding nodejs and socket.io!

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1 Answer

  1. Editorial Team

    The problem is because of Express now being a function.

    You need to do the following:

    var express = require('express');
var app = express();
var server = app.listen(3000);

var io = require('socket.io').listen(server);
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