socket.io.js not found (404) - express

Question

I am referring to an issue that has been asked many times but the solutions posted elsewhere are not resolving my problem ie socket.io.js not found.
The error message is
GET http://127.0.0.1:3000/socket.io/socket.io.js 404
Any help would be appreciated.
I referenced socket.io.js in my JADE file:
script(src='http://code.jquery.com/jquery.js')
script(src='http://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js')
script(src='/socket.io/socket.io.js')
script(src='/javascripts/sockets/client.js') // this is in public folder
In my App.js file:
var express = require('express');
io = require('socket.io');
http = require('http');
app = express();
server = http.createServer(app);
io = io.listen(server);
server.listen(app.get('port'), function(){
console.log("Express server listening on port " + app.get('port'));
});
app.use(express.static(path.join(__dirname, 'public')));
These are the versions I am using:
"express": "~4.13.1",
"jade": "~1.11.0",
"morgan": "~1.6.1",
"serve-favicon": "~2.3.0",
"socket.io": "0.9.10"
Some additional info:
In my app.js: I referenced the server socket
// set up our socket server
require('./public/javascripts/sockets/server')(io);
'/javascripts/sockets/client.js' is my client socket:
var socket = io.connect('/');
socket.on('message', function (data) {
data = JSON.parse(data);
$('#messages').append('<div class="'+data.type+'">' + data.message +
'</div>');
});
$(function(){
$('#send').click(function(){
var data = {
message: $('#message').val(),
type:'userMessage'
};
socket.send(JSON.stringify(data));
$('#message').val('');
});

Answer 1

You shouldn't be using the socket.io package for this as it is primarily intended to construct a socket.io server instance. Instead you should be using socket.io-client which was specifically made to be used as the client socket.
I would recommend using bower to install this instead of npm as bower is made for front-end package management. Inside your project directory execute the following
note: If you don't have bower installed you'll need to install it globally npm i -g bower
bower init
bower install --save socket.io-client
Then you should make the bower_components directory created by installing the socket.io-client a static directory
server.use(express.static(path.join(__dirname, 'bower_components')));
Then change
script(src='/javascripts/sockets/client.js') // this is in public folder
to
script(src='/bower_components/socket.io-client)
Additionally, you're mixing your server and app variables. You should be using whatever variable your socket.io was created using, in this case you're using server so you should be using that. Your server file is mostly incorrect as you're instantiating many global values and you've created your io instance incorrectly.
var express = require('express');
var app = express();
var server = require('http').Server(app);
var io = require('socket.io')(server);
var port = process.env.PORT || 3000;
server.use(express.static(path.join(__dirname, 'public')));
server.use(express.static(path.join(__dirname, 'bower_components')));
server.listen(port, function(){
console.log('Express server listening on port ' + port);
});