drupal/core/modules/toolbar/js/views/BodyVisualView.es6.js

/**
 * @file
 * A Backbone view for the body element.
 */

(function ($, Drupal, Backbone) {
  Drupal.toolbar.BodyVisualView = Backbone.View.extend(
    /** @lends Drupal.toolbar.BodyVisualView# */ {
      /**
       * Adjusts the body element with the toolbar position and dimension changes.
       *
       * @constructs
       *
       * @augments Backbone.View
       */
      initialize() {
        this.listenTo(this.model, 'change:activeTray ', this.render);
        this.listenTo(
          this.model,
          'change:isFixed change:isViewportOverflowConstrained',
          this.isToolbarFixed,
        );
      },

      isToolbarFixed() {
        // When the toolbar is fixed, it will not scroll with page scrolling.
        const isViewportOverflowConstrained = this.model.get(
          'isViewportOverflowConstrained',
        );
        $('body').toggleClass(
          'toolbar-fixed',
          isViewportOverflowConstrained || this.model.get('isFixed'),
        );
      },

      /**
       * {@inheritdoc}
       */
      render() {
        $('body')
          // Toggle the toolbar-tray-open class on the body element. The class is
          // applied when a toolbar tray is active. Padding might be applied to
          // the body element to prevent the tray from overlapping content.
          .toggleClass('toolbar-tray-open', !!this.model.get('activeTray'));
      },
    },
  );
})(jQuery, Drupal, Backbone);