ajax_dependencies

Drupal's AJAX forms support is pretty nifty! But it's harder than it has to be, requiring manual element wrapping and custom callbacks even for the simplest form.

The `ajax_dependencies` module makes it easy. Just declare which form elements depend on each other, and it takes care of the rest. Every time an element changes, every element dependent on it will be replaced via AJAX.

This module deals easily with even complicated cases. If multiple elements need to change at once, that just works. If dependencies chain—A depends on B depends on C—the implicit dependency of A on C will just work.