NodeJS async comparisons

aync.js

'use strict';

const promisify = require('util').promisify;

const delay = (interval, cb) => {
  console.log(`Waiting ${interval}s`);
  setTimeout(() => cb(null, interval), interval);
}
const delayAsync = promisify(delay);

// ----------------------------------------------------

// let result1, result2, result3;
// delay(1000, (err, result) => {
//   result1 = result;
//   console.log(`Got result: ${result1}`)
// });
// delay(2000, (err, result) => {
//   result2 = result;
//   console.log(`Got result: ${result2}`)
// });
// delay(3000, (err, result) => {
//   result3 = result;
//   console.log(`Got result: ${result3}`)
// });
// console.log('Sum:', result1 + result2 + result3)

// ----------------------------------------------------

// let result1, result2, result3;
// delay(1000, (err, result) => {
//   result1 = result;
//   console.log(`Got result: ${result1}`)
//   delay(2000, (err, result) => {
//     result2 = result;
//     console.log(`Got result: ${result2}`)
//     delay(3000, (err, result) => {
//       result3 = result;
//       console.log(`Got result: ${result3}`)
//       console.log('Sum:', result1 + result2 + result3)
//     });
//   });
// });

// ----------------------------------------------------

// let result1, result2, result3;
// delayAsync(1000)
//   .then(result => {
//     result1 = result;
//     console.log(`Got result: ${result1}`)
//     return delayAsync(2000)
//   })
//   .then(result => {
//     result2 = result;
//     console.log(`Got result: ${result2}`)
//     return delayAsync(3000)
//   })
//   .then(result => {
//     result3 = result;
//     console.log(`Got result: ${result3}`)
//     console.log('Sum:', result1 + result2 + result3)
//   });

// ----------------------------------------------------

// const parallelDelays = [
//   delayAsync(1000),
//   delayAsync(2000),
//   delayAsync(3000)
// ];

// Promise.all(parallelDelays)
//   .then(results => {
//    console.log(`Got results: ${results}`);
//    console.log('Sum:', results[0] + results[1] + results[2])
//   });

// ----------------------------------------------------

// (async function() {
//   let result1 = await delayAsync(1000);
//   console.log(`Got result: ${result1}`)

//   let result2 = await delayAsync(2000);
//   console.log(`Got result: ${result2}`)

//   let result3 = await delayAsync(3000);
//   console.log(`Got result: ${result3}`)
//   console.log('Sum:', result1 + result2 + result3)
// }());

// ----------------------------------------------------

// (async function() {
//   const parallelDelays = [
//     delayAsync(1000),
//     delayAsync(2000),
//     delayAsync(3000)
//   ];

//   let results = await Promise.all(parallelDelays)
//   console.log(`Got results: ${results}`)
//   console.log('Sum:', results[0] + results[1] + results[2])
// }());