Владимир Сергеевич

var list_of_items_to_process = [ 1, 2, 3, 4, 5 ];

function asyncMap(list, exec, callback) {
	var processed = 0;

	list.forEach(function(current, index, array) {
		exec(current, index, array, innerCallback.bind(index));
	})

	function innerCallback(result) {
		list[this] = result;
		processed++;
		if (processed === list.length) {
			callback(list);
		}
	}
}

function processor(value, index, array, callback) { 
	var result;
	setTimeout(function() { 
		result = value*Math.round(Math.random()*10);
		console.log(result)
		callback(result); 
	}, 500*value); 
}

function mainCallback(values) {
	console.log(values);
}

asyncMap(list_of_items_to_process, processor, mainCallback)

function asyncMap(list, exec, callback) {
  var processed = 0;

  list.forEach(function(current, index, array) {
    exec(current, index, array, innerCallback.bind(index));
  })

  function innerCallback(result) {
    list[this] = result;
    processed++;
    if (processed === list.length) {
      callback(list);
    }
  }
}

function processor(value, index, array, cb) {
  GMaps.geocode({
    address: value.address + " " + value.city + " " + value.zip,
    callback: function(results, status) {
      if (status == 'OK') {
        cb(results);
      } else {
        cb(false);
      }
    }
  });
}

function mainCallback(values) {
  values.forEach(function(value) {
    if (!value) return;

    var latlng = results[0].geometry.location;
    map.setCenter(latlng.lat(), latlng.lng());

    markers_data.push({
      id: value.id,
      lat: latlng.lat(),
      lng: latlng.lng(),
      title: value.name,
      icon: {
        size: new google.maps.Size(32, 32),
        url: icon
      },
      infoWindow: {
        content: ''
      }
    });
  });
}

asyncMap(items, processor, mainCallback)