Branching inside promise chain (JavaScript, Bluebirdjs)

promises_branching.js

var Promise = require('bluebird');

console.log('=== Branching promises demo ===');

function getNameById(id) {
  return Promise.resolve("Ziutek");
}

/*
Add missing data to object.
*/
Promise
  .resolve({ id: '123' }) // starting with object with just id
  .then( (data) => {
    // Condition
    if (!data.name) { // No name present? Let's fetch it
      // and return array of promises
      return [Promise.resolve(data), getNameById(data.id)];
    }

    // this promise always returns array of promises: [data, name]
    return [Promise.resolve(data), null];
  })
  .spread((data, name) => { // here we will merge promises    
    return {
      person_id: data.id,
      person_name: name
    }
  })
  .then(console.log);