Async foreach

gistfile1.js

Array.prototype.asyncEach = function(iterator) {
  var list    = this,
      n       = list.length,
      i       = -1,
      calls   = 0,
      looping = false;

  var iterate = function() {
    calls -= 1;
    i += 1;
    if (i === n) return;
    iterator(list[i], resume);
  };

  var loop = function() {
    if (looping) return;
    looping = true;
    while (calls > 0) iterate();
    looping = false;
  };

  var resume = function() {
    calls += 1;
    if (typeof setTimeout === 'undefined') loop();
    else setTimeout(iterate, 1);
  };
  resume();
};


사용방법
list.asyncEach(function(item, resume) {
  // handle item
  resume();
});