simple demo to batch promises as opposed to promise.all

batcher.js

job = (input, batchNumber) => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log('Running batch ',batchNumber, 'processing ', input)
      resolve('completed ' + input)
    }, 1000)
  })
}

async function batcher(inputArray, fn, batchSize) {
  const results = []
  batchNumber = 0
  for (let i = 0; i < inputArray.length; i += batchSize) {
    batchNumber++
    batchRun = inputArray.slice(i, i + batchSize)
      .map(input => fn(input, batchNumber))
    results.push(...await Promise.all(batchRun))
  }
 return results 
}

inputArray = []
for (let i = 1; i < 100; i++) {
  inputArray.push(i)
}

batcher(inputArray, job, 7)
  .then(console.log)