Our AJAX Drupal form could also trigger JS callbacks. See how in this video.
The idea is though not just to be another platform with some boring videos but all the videos to be inspired by real-world problems. That means something that you will most probably need if you work with Drupal. We want you to be successful and we want to teach you everything we know about Drupal!
So watch the videos, try to follow and reproduce, ask questions and you will see you will be able to conquer this wonderful sea that Drupal 8 is.