socket.io undefined and refusing connection - html

Question

I am using socket.io to display a message but when I run node server.js it does not console log any of the output message. I have attached my chat.html, server.js and main.js file to show the socket.io code.
chat.html
<script src="http://localhost:54159/socket.io/socket.io.js"></script>
<script src="js/main.js"></script>
server.js
const http = require('http');
const express = require('express');
const socketio = require('socket.io');
const app = express();
const server = http.createServer(app);
const io = socketio(server);
app.use(express.static(path.join(__dirname, 'public')));
io.on('connection', (socket) => {
console.log('New web socket connection...');
socket.emit('message', 'Welcome to Chat Room!');
});
const PORT = 54159 || process.env.PORT;
server.listen(PORT, () => console.log(`Server running on port ${PORT}`));
main.js
const socket = io();

Answer 1

OK, I guess I'll summarize the recommended changes our exchange in the comments:
Change this:
<script src="http://localhost:54159/socket.io/socket.io.js"></script>
to this:
<script src="/socket.io/socket.io.js"></script>
That removes the need for you to specify the port (which was incorrect anyway).
Change:
/public/chat.html
to:
/chat.html
so that it matches up with where your express.static() line is looking. For /public/chat.html to work, chat.html would have to be located in public/public/chat.html on your server's hard drive, but I assume it's not and it's likely in public/chat.html. Your express.static() line is pointing at public so that's the top of the tree it looks in. Any other paths in the URL are relative to that.
And, anytime you make a change in client or server code, make sure and restart your server to make sure all recent changes are being used.
If you're unsure at all about what port your server is running on, then look at the results of this when your server starts up:
console.log(`Server running on port ${PORT}`)
That will tell you port its running on. The brackets log reference to a port is probably brackets connected to the nodejs debugger which will be on a different port from your web server.