edlp_d8/core/modules/toolbar/js/views/MenuVisualView.es6.js

/**
 * @file
 * A Backbone view for the collapsible menus.
 */

(function ($, Backbone, Drupal) {
  Drupal.toolbar.MenuVisualView = Backbone.View.extend(/** @lends Drupal.toolbar.MenuVisualView# */{

    /**
     * Backbone View for collapsible menus.
     *
     * @constructs
     *
     * @augments Backbone.View
     */
    initialize() {
      this.listenTo(this.model, 'change:subtrees', this.render);
    },

    /**
     * @inheritdoc
     */
    render() {
      const subtrees = this.model.get('subtrees');
      // Add subtrees.
      Object.keys(subtrees || {}).forEach((id) => {
        this.$el
          .find(`#toolbar-link-${id}`)
          .once('toolbar-subtrees')
          .after(subtrees[id]);
      });
      // Render the main menu as a nested, collapsible accordion.
      if ('drupalToolbarMenu' in $.fn) {
        this.$el
          .children('.toolbar-menu')
          .drupalToolbarMenu();
      }
    },
  });
}(jQuery, Backbone, Drupal));