Promises.js

gistfile1.js

var Promise = function() {
  
  var response = null,
      successCallback = null;

  return {
    resolve: function(value) {
      response = value;

      if(successCallback) {
        successCallback(response);
        successCallback = null;
      }
    },
    success: function(callback) {
      if(!response) {
        successCallback = callback;
      } else {
        callback(response);
      }
    }
  };

};