wordpress - wp_nav_menu change sub-menu class name?

Question

Is there a way to change the child <ul class="sub-menu"> generated by WordPress itself to a custom class name?

I know the parent <ul> you can remove or change the name with 'menu_class' => 'newname'.

I couldn't find the answer. Itried 'submenu_class' => 'customname'. It seems logic to me, but obviously that is no the right one.

any ideas?

Answer 1

There is no option for this, but you can extend the 'walker' object that WordPress uses to create the menu HTML. Only one method needs to be overridden:

class My_Walker_Nav_Menu extends Walker_Nav_Menu {
  function start_lvl(&$output, $depth) {
    $indent = str_repeat("", $depth);
    $output .= "
$indent<ul class="my-sub-menu">
";
  }
}

Then you just pass an instance of your walker as an argument to wp_nav_menu like so:

'walker' => new My_Walker_Nav_Menu()