socket.io.js not found in express - node.js

Question

my folder structure for socket.io is as following:
node_modules/socket.io/
my folder structure for socket.io.js is as following:
/node_modules/socket.io-client/dist/socket.io.js
var express = require('express');
var http= require('http').Server(express);
var io= require('socket.io') (http);
var app = express();
io.on('connection', function(socket){
socket.on('chat', function(msg){
io.emit('chat',msg);
});
});
io.on('disconnect', function() {
console.log('user is disconnected');
});
And view is as follows:
<script src="/node_modules/socket.io-client/dist/socket.io.js"></script>
<script src="/js/jquery-2.1.4.min.js"></script>
<script>
$(function(){
var socket= io();
$('form').submit(function(e){
e.preventDefault();
socket.emit('chat', $('#input').val());
$('#input').val('');
return false;
});
socket.on('chat', function(msg){
$('#sent').append(msg);
});
});
</script>
and errors are:
Failed to load resource: the server responded with a status of 404 (Not Found)
Uncaught ReferenceError: io is not defined

Answer 1

Without creating server you are creating socket instance ,you can pass app to your socket.js or you can export socket to other module and use accordingly....It should be like this
var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);

Answer 2

First off, a node.js server does not server ANY files by default. For a file to be served by the server, there must be a route handler that has code to send that particular file. So, that explains why this doesn't work:
<script src="/node_modules/socket.io-client/dist/socket.io.js"></script>
because there is no route handler in your server for the path "/node_modules/socket.io-client/dist/socket.io.js".
But, socket.io solves this problem for you. The socket.io server automatically installs a route for:
/socket.io/socket.io.js
And it will reach into that node_modules/socket.io/client directory and send the socket.io.js file when it sees the above request.
So, change your script tag to this:
<script src="/socket.io/socket.io.js"></script>
And, the socket.io server will automatically send the socket.io.js file from the dist directory.
It looks like your server initialization is also not correct because you don't pass express to your http server, you pass app. Change this:
var express = require('express');
var http= require('http').Server(express);
var io= require('socket.io') (http);
var app = express();
io.on('connection', function(socket){
socket.on('chat', function(msg){
io.emit('chat',msg);
});
});
io.on('disconnect', function() {
console.log('user is disconnected');
});
to this:
var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);
server.listen(80);
io.on('connection', function(socket){
socket.on('chat', function(msg){
io.emit('chat',msg);
});
});
io.on('disconnect', function() {
console.log('user is disconnected');
});
or, a bit simpler version:
var express = require('express');
var app = express();
var server = app.listen(80);
var io = require('socket.io')(server);
io.on('connection', function(socket){
socket.on('chat', function(msg){
io.emit('chat',msg);
});
});
io.on('disconnect', function() {
console.log('user is disconnected');
});