JavaScript "Counter" object for iterating over asynchronous tasks, so you can do something once they're done even if they don't complete in any known order.

counter.js

// calls `cb` after `next()` meets `end`
// useful for asynchronous iteration
var Counter = function(end, cb){
  this._count = 0;
  this.next = function(){
    this._count++;
    if(this._count === end){
      cb();
    }
  }
}

main.js

var counter = Counter(queue.length, function(){
  // runs when counter has been called as many times as there are items in queue
  console.log('Finished!');  
});

queue.forEach(function(item){
  asynchronous_stuff(function(results){
    // handle results
    counter.next();
  });
});