nested promise with promise.all

nested_promise.js

const promise = num => new Promise((resolve) => {
  setTimeout(() => { resolve(num) }, 500)
})

var arr1 = [1,2,3,4,5].map(x => promise(x))
arr1
var arr2 = [6,7,8,9,0].map(x => promise(x))
arr2
const resolvePromise = async function () {
  let a = await Promise.all(arr1)
  let b = await Promise.all(arr2)
  a
  b
  const result = await Promise.all([ a, b ])
  result
}

resolvePromise()