Working with promises

demo.js

const promises = [
  () =>
    new Promise(resolve =>
      setTimeout(() => {
        resolve(console.log(1));
      }, Math.floor(Math.random() * 2000) + 1000)
    ),
  
  () =>
    new Promise(resolve =>
      setTimeout(() => {
        resolve(console.log(2));
      }, Math.floor(Math.random() * 2000) + 1000)
    ),
 
  () =>
    new Promise(resolve =>
      setTimeout(() => {
        resolve(console.log(3));
      }, Math.floor(Math.random() * 2000) + 1000)
    ),
  
  () =>
    new Promise(resolve =>
      setTimeout(() => {
        resolve(console.log(4));
      }, Math.floor(Math.random() * 2000) + 1000)
    )
]

/*
Procress array in sequence.
Output:
1
2
3
4
Async/Await: **some time in ms**
*/
(async () => {
  console.time('Async/Await')

  for (let item of promises) {
    await item();
  }

  console.timeEnd('Async/Await')
})();

/*
Output:
?
?
?
?
Promise: **some time in ms**
*/
(() => {
  console.time('Promise')

  Promise.all(promises.map(i => i()))
    .then(() => {
     console.timeEnd('Promise')
  })
})();