function _handleExpandBegin( event ) {
    window.scrollTo( 0, 0 );
    var menu = event.target;
    _handleToggle( menu );
    if ( menu === _rootMenu ) {
      this.dispatchEvent( 'rootExpandBegin', { target: this } );
      _bodyDom.addEventListener( 'click', _handleBodyClick );
    }

    // TODO: Enable or remove when keyboard navigation is in.
    // If on a submenu, focus the back button, otherwise focus the first link.
    // var firstMenuLink;
    // if ( _activeMenu === _rootMenu ) {
    //   firstMenuLink = _activeMenuDom.querySelector( 'a' );
    // } else {
    //   firstMenuLink = _activeMenuDom.querySelector( 'button' );
    // }
    // firstMenuLink.focus();
  }
/**
   * Event handler for when FlyoutMenu expand transition begins.
   * Use this to perform post-expandBegin actions.
   * @param {Event} event - A FlyoutMenu event.
   */
Event handler for when FlyoutMenu expand transition begins.
Use this to perform post-expandBegin actions.
@param {Event} event - A FlyoutMenu event.
Event handler for when FlyoutMenu expand transition begins . Use this to perform post - expandBegin actions . @param { Event } event - A FlyoutMenu event .
function _handleExpandBegin( event ) {
    window.scrollTo( 0, 0 );
    var menu = event.target;
    _handleToggle( menu );
    if ( menu === _rootMenu ) {
      this.dispatchEvent( 'rootExpandBegin', { target: this } );
      _bodyDom.addEventListener( 'click', _handleBodyClick );
    }
  }
function _handleExpandBegin ( event ) { window . scrollTo ( 0 , 0 ) ; var menu = event . target ; _handleToggle ( menu ) ; if ( menu === _rootMenu ) { this . dispatchEvent ( 'rootExpandBegin' , { target : this } ) ; _bodyDom . addEventListener ( 'click' , _handleBodyClick ) ; } }
Event handler for when FlyoutMenu expand transition begins.
Event handler for when FlyoutMenu expand transition begins .
// TODO: Enable or remove when keyboard navigation is in. // If on a submenu, focus the back button, otherwise focus the first link. // var firstMenuLink; // if ( _activeMenu === _rootMenu ) { //   firstMenuLink = _activeMenuDom.querySelector( 'a' ); // } else { //   firstMenuLink = _activeMenuDom.querySelector( 'button' ); // } // firstMenuLink.focus();