How to add scroll IDs to WordPress menu anchors

Thank god.. i’ve solved it my own. this is the function i used to update the anchor tags.

function my_walker_nav($item_output, $item, $depth, $args) {
    $menu_locations = get_nav_menu_locations();

if(!empty( $item->description ))
    $description = $item->description;
else {
   $description = ''; 
}

 if ($item->menu_order == 1){

 $item_output = preg_replace('/<a /', '<a data-scroll-nav="'.$description.'" ', $item_output, 1);

}
    return $item_output;
}
add_filter('walker_nav_menu_start_el', 'my_walker_nav', 10, 4);