1. How should modules implement JavaScript in Drupal 9 and 10?

Drupal recommends modules to attach JavaScript logic using Drupal.behaviors. For instance, the code below demonstrates this approach:

(function ($, Drupal) {
  'use strict';

  Drupal.behaviors.exampleModule = {
    attach: function (context, settings) {
      $('.example', context).click(function () {
        $(this).next('ul').toggle('show');
      });
    }
  };

})(jQuery, Drupal);

2. When does Drupal call attached behaviors, and what parameters are passed?

Drupal core calls attached behaviors when the DOM is fully loaded. It passes two arguments: context (representing the DOM) and settings (containing server-side injected settings).

3. How is Drupal.attachBehaviors() called and when does it occur in Drupal 9 and 10?

Drupal.attachBehaviors() is called to attach all behaviors and is typically triggered after the DOM is loaded using $(document).ready().

(function ($, Drupal) {
  'use strict';

  // Attach all behaviors.
  $(document).ready(function () {
    Drupal.attachBehaviors(document, Drupal.settings);
  });

})(jQuery, Drupal);

4. How can behaviors be made efficient and run only once in Drupal 9 and 10?

To ensure behaviors run only once, developers can utilize jQuery.once().

(function ($, Drupal) {
  'use strict';

  Drupal.behaviors.syfyGlobalHideMenu = {
    attach: function (context, settings) {
      $('.nav-flyout', context).once('remove-modals').each(function () {
        $(document).keyup(function (e) {
          if (e.keyCode == 27) {
            $(this).removeClass('js-flyout-active');
          }
        });
      });
    }
  };

})(jQuery, Drupal);

5. Why is considering the context variable important in Drupal 9 and 10 behaviors?

The context variable contains the affected piece of HTML, and using it in jQuery selectors is crucial for efficient code.

(function ($, Drupal) {
  'use strict';

  Drupal.behaviors.syfyGlobalHideMenu = {
    attach: function (context, settings) {
      $(document, context).keyup(function (e) {
        if (e.keyCode == 27) {
          $('.nav-flyout', context).removeClass('js-flyout-active');
        }
      });
    }
  };

})(jQuery, Drupal);

These examples demonstrate how to adapt JavaScript code for Drupal 9 and 10, considering best practices and maintaining compatibility with these versions while addressing common questions about CMS and JavaScript integrationpt.