chainQvars.js

const delay = (delta) =>
  new Promise((resolve, reject) => {
    setTimeout(() => resolve(), delta)
  })

const d1 = delay(300).then(() => {
  console.log('1')
  return delay(300)
})

const d2 = d1.then(() => {
  console.log('2')
  return delay(300)
})

const d3 = d2.then(() => {
  console.log('3')
  return delay(300)
})