const express = require('express');

const { createServer } = require("http");

const { Server } = require("socket.io");

const app = express();

const httpServer = createServer(app);

const io = new Server(httpServer);

const port = process.env.PORT || 5000;

app.use(express.static(__dirname + '/latency_public'));

io.on('connection', socket => {

console.log(`connect ${socket.id}`);

socket.on('ping_from_client', () => {

socket.emit('pong_from_server');

});

socket.on('disconnect', () => {

console.log(`disconnect ${socket.id}`);

});

});

httpServer.listen(port, () => console.log(`server listening on port ${port}`));