最好循环浏览所有菜单项，以便您可以单独获取它们，如下所示。这将使您可以向ul和li项目添加类。

    <?php $myMenu = get_nav_menu_locations();

// \'main-menu\' is the name of your menu, you can find this under \'menu\' in the Dashboard of your Wordpress site
$menuID = $myMenu[\'main-menu\'];

$mainNav = wp_get_nav_menu_items($menuID);

?>
<ul>
    <?php foreach ($mainNav as $navItem): ?>

        <li>
            <a href="<?php echo $navItem->url; ?>"
              title="<?php echo $navItem->title; ?>">
              <?php echo $navItem->title; ?>
          </a>
      </li>
  <?php endforeach; ?>
</ul>

可能使用nav_walker 或打开过滤器wp_nav_menu_objects

这是一个简单的nav\\U walker，当在wp\\U nav\\U菜单上输出时，它会将菜单中每个链接的内容包装成一个范围

<?php
/**
 * Add_Span_Nav_Walker
 * wp_nav_menu walker-class to wrap contents of each menu-item link in span element
 */

class Add_Span_Nav_Walker extends Walker_Nav_Menu {

    function start_lvl( &$output, $depth = 0, $args = [] ) {
        $indent = str_repeat( "\\t", $depth );
        $output .= "\\n$indent\\n";
    }

    function end_lvl( &$output, $depth = 0, $args = [] ) {
        $indent = str_repeat( "\\t", $depth );
        $output .= "$indent\\n";
    }

    function start_el( &$output, $item, $depth = 0, $args = [], $id = 0 ) {
        $indent = ( $depth ) ? str_repeat( "\\t", $depth ) : \'\';

        $class_names = $value = \'\';

        $classes   = empty( $item->classes ) ? [] : (array) $item->classes;
        $classes[] = \'menu-item-\' . $item->ID;

        $class_names = join( \' \', apply_filters( \'nav_menu_css_class\', array_filter( $classes ), $item, $args ) );

        $class_names = $class_names ? \' class="\' . esc_attr( $class_names ) . \'"\' : \'\';

        $id = apply_filters( \'nav_menu_item_id\', \'menu-item-\' . $item->ID, $item, $args );
        $id = $id ? \' id="\' . esc_attr( $id ) . \'"\' : \'\';

        $output .= $indent . \'\';

        $attributes = ! empty( $item->attr_title ) ? \' title="\' . esc_attr( $item->attr_title ) . \'"\' : \'\';
        $attributes .= ! empty( $item->target ) ? \' target="\' . esc_attr( $item->target ) . \'"\' : \'\';
        $attributes .= ! empty( $item->xfn ) ? \' rel="\' . esc_attr( $item->xfn ) . \'"\' : \'\';
        $attributes .= ! empty( $item->url ) ? \' href="\' . esc_attr( $item->url ) . \'"\' : \'\';

        $item_output = $args->before;
        $item_output .= \'<li\' . $class_names . \'><a\' . $attributes . \'><span>\';
        $item_output .= $args->link_before . apply_filters( \'the_title\', $item->title, $item->ID ) . $args->link_after;
        $item_output .= \'</span></a>\';
        $item_output .= $args->after;

        $output .= apply_filters( \'walker_nav_menu_start_el\', $item_output, $item, $depth, $args );
    }


    function end_el( &$output, $item, $depth = 0, $args = [] ) {
        $output .= "\\n";
    }
}

<?php
if ( has_nav_menu( \'wpse288486_nav\' ) ) :
    wp_nav_menu( [
        \'theme_location\' => \'wpse288486_nav\',
        \'walker\'         => new Add_Span_Nav_Walker(),
    ] );
endif;