Serial promise with bluebird. The next function will only execute after the first is completed.

serial-promise.js

const Promise = require('bluebird')

function doWork (val) {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve(val)
    }, 2000)
  })
}

async function main () {
  const ok = await Promise.all(Array(10).fill(0))
    .map((_, i) => doWork(i), { concurrency: 1 })
  console.log(ok)
}

main().then(console.log).catch(console.error)