Can't find socket.io.js - node.js

Question

I'm making a web-app that makes use of nodejs, mongodb, socket.io, express and mongoose.
I can start my server and correctly get the wanted html file in my browser when browsing to my localhost.
The problem I have is getting my socket.io to work.
On my server side everything works fine : I get " info - socket.io started " in my terminal.
But when surfing to my browser I get this in my browser console
Failed to load resource: the server responded with a status of 404 (Not Found)
Uncaught ReferenceError: io is not defined
This is how i connect to socket.io.js
<script src="/socket.io/socket.io.js"></script>
and my map structure looks like this:
map
-app.js
-public
--index.html
-node_modules
--socket.io
--mongodb
--express
--jade
--mongoose
Does anyone knows what the mistake is I've made?
(it's actually the same problem as here: Node.js socket.io.js not found or io not defined )
Thanks in advance!
EDIT:
My code on the server side is this:
var app= require('express').createServer();
var io = require('socket.io').listen(app);
var mongoose = require('mongoose');
var db = mongoose.connect('mongodb://localhost/db');
app.listen(3030);
console.log("server started");
app.get('/',function(req,res){
res.sendfile(__dirname + '/public/index.html');
});
io.sockets.on('connection',function(socket){
console.log("connection made");
});
The first log, gets logged in the terminal ("server started"), but the second one ("connection made") doesn't get logged. So the connection isn't made.
I thought that was because of the wrong "set up" in my client side.

Answer 1

Check out the express migration guide 2->3
https://github.com/visionmedia/express/wiki/Migrating-from-2.x-to-3.x
Something like this should work
var express = require('express');
var app = express();
var http = require('http');
var server = http.createServer(app);
var io = require('socket.io').listen(server);
var mongoose = require('mongoose');
var db = mongoose.connect('mongodb://localhost/db');
server.listen(3030);
console.log("server started");
app.get('/',function(req,res){
res.sendfile(__dirname + '/public/index.html');
});
io.sockets.on('connection',function(socket){
console.log("connection made");
});

Answer 2

var app = express();
app.set('port', process.env.PORT || 3000);
...
var server = http.createServer(app).listen(app.get('port'), function(){
console.log("Express server listening on port " + app.get('port'));
});
var io = socket.listen(server);
io.sockets.on('connection', function () {
console.log('hello world im a hot socket');
});