Promise all in CoffeeScript

promise-all-coffeescript.coffee

subset = [
  'item1'
  'item2'
  'item3'
]
# uniform distribution of wait times
waitTimes = arrayRangeMap(subset.length, ->
  getRandomArbitrary(0.1, 0.3, 3) * 1000
)
Q = PromiseAllP(subset, executionBlock, waitTimes)

getRandomArbitrary = (min, max, fixed) ->
  fixed = fixed or 10
  (Math.random() * (max - min) + min).toFixed fixed

arrayRangeMap = (a, block) ->
  c = []
  while a--
    c[a] = block()
  c

Sleep = (time, block) ->
  stop = (new Date).getTime()
  while (new Date).getTime() < stop + time
    continue
  block()
  return

PromiseAllP = (items, block, waitTimes) ->
  promises = []
  index = 0
  items.forEach (item) ->
    promises.push ((item, i) ->
      new Promise((resolve, reject) ->
        if waitTimes and i < waitTimes.length + 1
          Sleep waitTimes[i - 1], ->
            block item, index, resolve, reject
        else
          block item, index, resolve, reject
        return
)
    )(item, ++index)
    return
  Promise.all promises

# execution on the item at index

executionBlock = (item, index, resolve, reject) ->
  resolve index: item

Q.then (results) ->
  console.log 'aggregated', results
  return
Q.catch (error) ->
  console.log error
  return

You can try out this script here.