Alternative Promise code

AA4-promises.js

/** Utility Functions **/
// Calls a method on an object
const call = method => value => value[method]();

/** Business Logic **/
const getUserAndFriendsAvatars = async user => {
  // get user
  const user = getUser(user);
  // get users friends
  const friends = user.then(call('friends'));

  //get users avatar
  const avatar = user.then(call('avatar'));

  // get the friends avatars
  const friendAvs = Promise.all(friends.then(fs => fs.map(call('avatar'))));

  // wait for everything to finish
  return Promise.join(avatar, friendAvs).then((a, as) => a.concat(as));
};