index.js

// Import packages
const express = require("express");
const socketIO = require("socket.io");
const path = require("path");

// Configuration
const PORT = process.env.PORT || 3000;
const INDEX = path.join(__dirname, 'index.html');

// Start server
const server = express()
  .use((req, res) => res.sendFile(INDEX) )
 .listen(PORT, () => console.log("Listening on localhost:" + PORT));

// Initiatlize SocketIO
const io = socketIO(server);

// Register "connection" events to the WebSocket
io.on("connection", function(socket) {
  io.emit('connected to my app');

  // Register "join" events, requested by a connected client
  // socket.on("join", function (room) {
  //   // join channel provided by client
  //   socket.join(room)
  //   // Register "image" events, sent by the client
  //   socket.on("image", function(msg) {
  //     // Broadcast the "image" event to all other clients in the room
  //     socket.broadcast.to(room).emit("image", msg);
  //   });
  // })
});