Using sockets with express in production environment(heroku) - node.js

Question

While working with localhost I used the following code to implement socket functionality-
Server Side
var express = require('express');
var app = express();
const io = require('socket.io')(5000);
Client Side
<script src="http://localhost:5000/socket.io/socket.io.js"></script>
<script>const socket = io.connect('http://localhost:5000');</script>
The above code worked fine for me locally. Earlier tried use the code given in the official documentation, but it did not work. I got a 404 error when trying to load socket.io.js file and it said 'io is not defined' on the client side. That code is given below-
Server Side
var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
Client Side
<script src="/socket.io/socket.io.js"></script>
<script>var socket = io.connect('http://localhost');</script>
Now I need to deploy the app to Heroku and don't know how to do the socket functionality. I tried both the above ways but none worked in Heroku. I am getting '404 error' and 'io is not defined'. The server-side code is written in ./app.js and client-side code written in ./public/index.html.
How do I get this socket functionality to work in Heroku and also why is the official code not even working locally?

Answer 1

Trying to get the same thing working, don't have all the answers but on heroku you need to grab the port from the environment variable.
// Needed for Heroku serving
if (process.env.PORT > 0)
port = process.env.PORT;
else
port = 5000;
// create the express server (app) and the socket io server (io)
const app = express();
const server = app.listen(port, () => {
console.log("Listening on port: " + port);
});
const io = require('socket.io')(server);
Client Side
const socket = socketIOClient('APPNAME.herokuapp.com:80');
socket.emit("MsgType", "Payload")