promise-emitters.js

let bookmarks = [b1, b2, b3];

// Emitter
save(bookmarks).on('data', (bookmark) => {
  // a bookmark saved
}).on('end', (bookmarks) => {
  // all bookmarks finished
});

// Promise with one input
// Can easily handle errors
save(bookmark)
  .then(doSomething, console.error)
  .then(doSomethingElse);

// Promise with multi input

// Returns an array of promises? Can handle errors single-y, but always overhead
save(bookmarks).map(p => p.then(doSomething, console.error).then(doSometingElse));

// Returns a promise for the completion of all tasks
// What happens if one save task fails? Promise represents a single computation, and exposing
// only an aggregate seems harder to handle errors, although easier to consume
save(bookmarks).then(bookmarks => bookmarks.map(doSomething))
  .then(bookmarks => bookmarks.map(doSomethingElse));