Indicator for non-empty tabs

fwiw, I attach js like the following, to a specific text area (Description) field to add/remove a class indicating content is present.

/**
 * Indicate whether Description tabs have content.
 */
(function (Drupal, once) {
  Drupal.behaviors.multilingual_form = {
    attach: function () {

      once('multilingual-form', 'html').forEach(function () {

        // Set initial indicator state, and add change listener.
        jQuery('.field--name-field-description.horizontal-tabs-panes details textarea').each(function(){
          const tab_details = jQuery(this).closest('details');
          const tab_details_id = '#' + tab_details.attr('id');
          setNavItemForTextArea(tab_details_id);
        }).on('change',function(){
          const tab_details = jQuery(this).closest('details');
          const tab_details_id = '#' + tab_details.attr('id');
          setNavItemForTextArea(tab_details_id);
        });

        // Set has-content class based on contents of tab textarea.
        function setNavItemForTextArea(tab_details_id) {
          const navItemSelector = 'a[href="' + tab_details_id + '"]';
          const hasContent = jQuery(tab_details_id + ' textarea').val() !== '';
          if (hasContent) {
            jQuery(navItemSelector).addClass('has-content');
          }
          else {
            jQuery(navItemSelector).removeClass('has-content');
          }
        }

      });
    }
  };
})(Drupal, once);