Promise.all & async.parallel

parallel.js

import async from 'async';

const ap = () => {
  async.parallel([
    (cb) => {
      setTimeout(() => {
        console.log(2)
        cb(2, 2);
      }, 2000);
    },

    (cb) => {
      setTimeout(() => {
        console.log(3)
        cb(null, 3);
      }, 3000);
    },

    (cb) => {
      setTimeout(() => {
        console.log(1)
        cb(null, 1);
      }, 1000);
    }
  ]).then((results) => {
    console.log(results);
  }).catch((e) => console.error(e));
}

const pall = () => {
  Promise.all([
    new Promise((resolve, reject) => {
      setTimeout(() => {
        console.log(2)
        reject(2)
      }, 2000);
    }),

    new Promise((resolve, reject) => {
      setTimeout(() => {
        console.log(3)
        resolve(3)
      }, 3000);
    }),

    new Promise((resolve, reject) => {
      setTimeout(() => {
        console.log(1)
        resolve(1)
      }, 1000);
    })
  ]).then((results) => {
    console.log(results);
  }).catch((e) => console.error(e));
}

// ap();
pall();
// we can use multiple await, but await will return error callback only when the longest promise has been finised ( not fail fast )