Unable to connect Socket.io, where is the error?

Question

JavaScript

I connect socket.oi. It does not display any errors, but it does not write anything to the console either, here is the code, the page files are signed. The layout.jade file is cross-cutting for all pages.
app.js

var express = require('express'),
    app = require('express')(),
    http = require('http').Server(app),
    io = require('socket.io')(http),
    start = require('./routes/index.js');

app.use('/', start);

io.on('connection', function(socket){
    console.log('a user connected');
    socket.on('disconnect', function(){
        console.log('user disconnected');
    });
});

var server = app.listen(3000, function () {
    var host = server.address().address;
    var port = server.address().port;
});

module.exports = app;

layout.jade

doctype html
html(lang="en")
    head
        script(type="text/javascript" src="https://cdn.socket.io/socket.io-1.4.3.js")
        script.
            var socket = io();

    body
        block content

Answer 1

It's not entirely clear why you are using socketio here
var socket = io('ws://example.ru:3000')