mix.coffee

Array::forEachAsync = (each, context) ->
  copy  = @slice()
  index = -1

  do next = ->
    return if copy.length == 0

    process.nextTick ->
      item   = copy.shift()
      index += 1

      each.call context, item, index, next

[0..2].forEach (i) ->
  [0..5].forEachAsync (value, index, next) ->
    process.nextTick =>
      console.log i, value
      next()

# 0 0
# 1 0
# 2 0
# 0 1
# 1 1
# 2 1
# 0 2
# 1 2
# 2 2
# 0 3
# 1 3
# 2 3
# 0 4
# 1 4
# 2 4
# 0 5
# 1 5
# 2 5