add_filter('nav_menu_css_class', 'add_additional_class_on_li', 1, 3);
function add_additional_class_on_li($classes, $item, $args) {
if($args->add_li_class) {
$classes[] = $args->add_li_class;
}
return $classes;
}
add_filter( 'nav_menu_link_attributes', 'w3_ad_a_class', 10, 3 );
function w3_ad_a_class( $atts, $item, $args ) {
if($args->add_a_class) {
// $class = 'main-menu__a'; // or something based on $item
$atts['class'] = $args->add_a_class;
}
return $atts;
}