Check if a server is ready in node.js

serverReady.js

import http from 'http';

function delay(time) {
  return new Promise(((resolve) => {
    setTimeout(resolve, time);
  }));
}

function serverReady() {
  return new Promise(((resolve) => {
    async function checkReady() {
      process.stdout.write('...');
      await delay(500);
      const req = http.get({
        hostname: 'localhost',
        port: parseInt(process.env.port),
        path: '/',
      }, (res) => {
        if (res.statusCode === 200) {
          resolve();
        } else {
          return checkReady();
        }
      });
      req.on('error', () => checkReady());
    }
    checkReady();
  }));
}