app.js

const express = require('express');
const http = require('http');

const PORT = process.env.PORT || 3000;

const app = express();
const server = http.createServer(app);
const io = require('socket.io')(server);

app.use(express.static("public"))

app.get('/', (req, res) => {
    res.sendFile(__dirname + '/public/index.html');
})

let connectedPeers = [];

io.on('connection', (socket) => {
    connectedPeers.push(socket.id);
    console.log(connectedPeers);

    socket.on('disconnect', () => {
        console.log("user diconnected");

        const newConnectedPeers = connectedPeers.filter((peerSocketId) => {
            return peerSocketId !== socket.id;
        })

        connectedPeers = newConnectedPeers;
        console.log(connectedPeers);
    })
});

server.listen(PORT, () => {
    console.log('listening on ${PORT}')
});