Append code to app.js for enable HTTP or HTTPS

express_https.js

// start the server HTTP & HTTPS
const http = require('http');
const https = require('https');
const fs = require('fs');

var credentials = {
  key: fs.readFileSync('./ssl-cert.key'),
  cert: fs.readFileSync('./ssl-cert.cert')
};

// use HTTP
// http.createServer(app).listen(80);

// use HTTPS
https.createServer(credentials , app).listen(443);
console.log("Express is running ...");