WebSocketsDemo

client.js

var wsUri = "ws://127.0.0.1:8999";
ws = new WebSocket(wsUri);
ws.onopen = (e) => console.log(e)
ws.onmessage = (e) => console.log(e)

server.js

import express from 'express';
import http from 'http';
import WebSocket from 'ws';

const app = express();
app.use(express.static('ui'));
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });

app.get('/', function (req, res) {
    res.sendFile( __dirname + "/" + "index.html" );
 })

wss.on('connection', (ws) => {

    ws.on('message', (message) => {

        console.log('received: %s', message);
        ws.send(`Hello, you sent -> ${message}`);
    });
    ws.send('Hi there, I am a WebSocket server');
});

server.listen(process.env.PORT || 8999, () => {
    console.log(`Server started on port ${server.address().port} :)`);
});