6-series.js

'use strict';

// Emulate Asynchronous calls

const pause = () =>
  new Promise((resolve) =>
    setTimeout(resolve, Math.floor(Math.random() * 1000)),
  );

// Asynchronous functions

const readConfig = async (name) => {
  await pause();
  console.log('(1) config loaded');
  return { name };
};

const doQuery = async (statement) => {
  await pause();
  console.log(`(2) SQL query executed: ${statement}`);
  return [{ name: 'Kiev' }, { name: 'Roma' }];
};

const httpGet = async (url) => {
  await pause();
  console.log(`(3) Page retrieved: ${url}`);
  return '<html>Some archaic web here</html>';
};

const readFile = async (path) => {
  await pause();
  console.log(`(4) Readme file loaded: ${path}`);
  return 'file content';
};

// Usage

const main = async () => {
  const config = await readConfig('myConfig');
  const res = await doQuery('select * from cities');
  const json = await httpGet('http://kpi.ua');
  const file = await readFile('README.md');
  console.log('Done');
  console.dir({ config, res, json, file });
};

main();