Function to asynchronously iterate over a collection

eachAsync.js

function eachAsync(collection, iterator, callback) {
  var iterate = function(i) {
    setTimeout(function() {
      iterator(collection[i]);
      if (i < collection.length) {
        iterate(i + 1);
      } else {
        callback();
      }
    }, 0);
  };

  iterate(0);
}