Promise.series - Synchronous version of Promise.all

promise-series.js

const PromiseSeries = (arr) => {
  if (arr.length > 1) {
    const target = arr[0]
    const rest = arr.slice(1)
    return target.then(() => PromiseSeries(rest))
  } else {
    return arr[0]
  }
}

usage.js

const test1 = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log('Done with test1')
      resolve()
    }, 1000)
  })
}

const test2 = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log('Done with test2')
      resolve()
    }, 1000)
  })
}


const failTest = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log('Fail with failTest')
      reject(new Error('Fail with failTest'))
    }, 1000)
  })
}

PromiseSeries([test1(), test2()])
  .then(() => console.log('All Done!'))
  .catch(err => console.error(err))
/**
  * 'Done with test1'
  * 'Done with test2'
  * 'All Done!'
  */
  
PromiseSeries([test1(), failTest(), test2()])
  .then(() => console.log('All Done!'))
  .catch(err => console.error(err))
/**
  * 'Done with test1'
  * 'Error: Fail with failTest'
  */