Process lots of promises effectively

chunk.js

import chunk from 'lodash.chunk'

export const processInChunks = async (array, handlerFn, { chunkSize = 5 } = {}) => {
  const result = []
  for (const dataChunk of chunk(array, chunkSize)) {
    result.push(...await Promise.all(dataChunk.map(handlerFn)))
  }
  return result
}

// Example of using
//
// const files = [ ... ] // lot of files that would generate lot of promises that you don't want to run at once
// 
// await processInChunks(files, async fileKey => {
//   await storageService.deleteFile(key)
//})