Drupal behaviors

Question

• What are Drupal behaviors at all?
• What type of service layer it offers to module developers?
• What type of relation it maps to jQuery.ready

Answer 1

Looking for a similar answer and arrived here, still without clues. Finally found a little more explanation (and examples) from an article here: https://benmarshall.me/drupal-behaviors/

I am not the original author, so I can only quote some texts:

What are Drupal Behaviors?

In short, Drupal.behaviors is a more modular and better way to implement jQuery.ready. Unlike jQuery.ready which only runs once when the DOM is ready for manipulation, Drupal.behaviors can be ran multiple times during page execution. Even better, they can be ran whenever new DOM elements are inserted into the document (i.e. AJAX driven content).

Drupal.behaviors can also override or even extend an existing behavior. So for instance, if a module behavior adds a bounce effect on all links, another module could replace that behavior with a different bounce effect.

Another added bonus of Drupal.behaviors (starting in Drupal 7), is the ability to use the drupal_add_js (PHP) or Drupal.settings.modulename (JS) and pass settings as a second parameter (the first being the context) to the behavior.