promise-all-spike.js

const createTimeoutPromise = (time) => new Promise((resolve) => {
  setTimeout(() => {
    console.log(`resolved after ${time} secs`)
    resolve(time)
  }, time)
})

console.log('creating promises')
const promiseB = createTimeoutPromise(2000)
const promiseC = createTimeoutPromise(3000)
const promiseA = createTimeoutPromise(100)

const startsAfterPromiseATime = 200
setTimeout(() => {
  console.log('promise.all them...')
  Promise.all([promiseA, promiseB, promiseC]).then((values) => {
    console.log(values)
  })
}, 200)

// creating promises
// resolved after 100 secs
// promise.all them...
// resolved after 2000 secs
// resolved after 3000 secs
// [ 100, 2000, 3000 ]