Socket.IO can't connect to server when running Express - node.js

Question

I am trying to write a little app using Node.js, Express.js and Socket.IO.
The server runs fine and I can serve HTML and other static content. But I'm having a hell of a time getting the clients to connect via Socket.IO to the server.
When I don't use Express it works fine, but with Express I can't seem to get everything to cooperate. I am not sure if there are some special considerations when using Express and Socket.IO in conjunction.
Part of me thinks this could be a route issue?
It looks like when the socket tries to connect it is 404'ing:
GET http://localhost:3000/socket.io/1/?t=1403186531515 400 Bad Request 1ms
Server code:
var express = require('express')
, app = express()
, http = require('http')
, server = http.createServer(app).listen(3000)
, io = require('socket.io').listen(server)
, favicon = require('static-favicon')
, logger = require('morgan')
, cookieParser = require('cookie-parser')
, session = require('express-session')
, routes = require('./routes/index')
, path = require('path')
, bodyParser = require('body-parser');
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'hjs');
app.use(favicon());
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded());
app.use(cookieParser());
app.use(session({secret: 'keyboard cat'}));
app.use(require('less-middleware')(path.join(__dirname, 'public')));
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', routes);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: err
});
});
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
res.status(err.status || 500);
res.render('error', {
message: err.message,
error: {}
});
});
io.sockets.on('connection', function (socket) {
//message new connection
socket.emit('message', { message: 'Message from server.' });
//message all connections
socket.on('send', function (data) {
io.sockets.emit('message', data);
});
});
Client code:
** html and other js omitted **
<script src="//cdnjs.cloudflare.com/ajax/libs/socket.io/0.9.16/socket.io.min.js"></script>
<script>
var socket = io.connect('http://localhost:3000');
</script>
I have also tried
var socket = io.connect('ws://localhost:3000');
To no avail.
Thanks for any help!

Answer 1

Not sure why you use CDN on client, but you can use the local resource (served in backstage by socket.io)
So replace your script tags with:
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect(); // or just io();
</script>
You can get more help in Socket.io Get Started simple chat example

Answer 2

Try swapping the order of when you bind the server to a port:
var express = require('express')
, app = express()
, http = require('http')
, server = http.Server(app)
, io = require('socket.io').listen(server)
server.listen(3000);
Shoutout to Doug Wilson for his comment on GitHub which helped me solve this issue.

Answer 3

just try :
var socket = io.connect();