a simple promise

function deferred() {
  var callbacks = {
    done: [],
    fail: [] 
  }; 

  var promise = {
    done: function(callback) {
      callbacks.done.push(callback);
      return promise;
    }, 

    fail: function(callback) {
      callbacks.fail.push(callback);
      return promise;
    }  
  }; 

  return {
    resolve: function() {
      var i = 0, cb;
      for(;cb = callbacks['done'][i++];) {
        cb.apply(this, arguments);
      }  
    }, 

    reject: function() {
      var i = 0, cb;
      for(;cb = callbacks['fail'][i++];) {
        cb.apply(this, arguments);
      }  
    }, 

    promise: promise 
  }; 
}