gistfile1.swift

// @info
//   Asynchronously iterate over each item of an array or an array-like object.
//   The order in which items are iterated is guaranteed to match array order.
var iterateSeries = function (array, iterator, callback) {
  array =  Array.prototype.slice.call(array, 0);

  if (array.length === 0) {
    if (callback) callback();
  }
  else {
    var index = 0;

    var error = function(error) {
      if (callback) callback(error);
    };

    var next = function() {
      index += 1;

      if (index >= array.length) {
        if (callback) callback();
      }
      else {
        iterator(array[index], once(next), once(error));
      }
    };

    iterator(array[index], once(next), once(error));
  }
};