promises.js

var Promise = require('bluebird');


var facebookAsync = function() {
  var dfd = Promise.defer();

  FB.login(function(err, user) {
    if (err) {
      dfd.reject(err);
    } else {
      dfd.resolve(user);
    }
  });

  return dfd.promise;
};



facebookAsync.then(function(user) {
  console.log('User', user);
});





function FB(callback) {
  // this.init();
}

FB.prototype.login = function(callback) {
  var user = {
    name: 'PatrickJS'
  };
  setTimeout(function() {
    callback(null, user);
  }, 3000);
};