Node.js - Hello World example

const http = require("http");
const HOSTNAME = process.env.HOSTNAME || "localhost";
const PORT = process.env.PORT || 3000;

const server = http.createServer((request, response) => {
  response.statusCode = 200;
  response.setHeader("Content-Type", "text/plain");
  response.end("Hello World");
});

server.listen(PORT, HOSTNAME, () => {
  console.log(`Server running at http://${HOSTNAME}:${PORT}/`);
});