example.js

var Q = require('q');

function buildStructure(house) {
  var deferred = Q.defer();
  
  setTimeout(function () {
    console.log('build structure');
    // pretend like we're persisting this to a database
    house.id = 'ABCD12345';
    house.rooms = house.rooms || []; // make sure this is an array
    deferred.resolve(house);
  }, 1000);

  return deferred.promise;
}

function paintHouse(house) {
  var deferred = Q.defer();
  
  setTimeout(function () {
    console.log('paint the house');
    house.color = "house-color";
    deferred.resolve(house);
  }, 1000);

  return deferred.promise;
}
    
function buildRoom(room) {
  var deferred = Q.defer();

  setTimeout(function () {
    room.id = 'ROOM_' + room.name.replace(/\D/g, '');
    deferred.resolve(room);    
  }, 1000);

  return deferred.promise;
}
    
function buildHouse(house) {
  return Q.when(house)
    .then(buildStructure)
    .then(paintHouse)
    .then(function(house) { // could replace this with `.get('rooms')` using Bluebird
      return Q.all(house.rooms.map(buildRoom));
    })
    .then(function () { // could replace this with `.return(house)` using Bluebird
      return house;
    });
}

buildHouse({});