Classic Theme Navigation Menus

Use this when adding or reviewing classic theme menus, header navigation, footer navigation, social/menu locations, mobile menu toggles, menu filters, or custom walkers.

When to Use This Skill

• Registering menu locations in a classic theme.
• Rendering wp_nav_menu() in header.php, footer.php, or a template part.
• Adding a mobile menu toggle.
• Preventing WordPress from silently falling back to page lists.
• Adding classes/attributes to menu links.
• Reviewing custom Walker_Nav_Menu code.

Register Menu Locations

Register locations on after_setup_theme.

add_action( 'after_setup_theme', 'mytheme_register_menus' );

function mytheme_register_menus() {
	register_nav_menus(
		array(
			'primary' => __( 'Primary menu', 'textdomain' ),
			'footer'  => __( 'Footer menu', 'textdomain' ),
		)
	);
}

Rules:

• Location keys must be strings.
• Prefix unusual location keys if they might collide in shared code.
• register_nav_menus() automatically adds theme support for menus.
• Do not register menu locations from template files.

Render a Menu

Use wp_nav_menu() with an explicit location and fallback behavior.

if ( has_nav_menu( 'primary' ) ) :
	?>
	<button
		class="menu-toggle"
		type="button"
		aria-controls="primary-menu"
		aria-expanded="false"
	>
		<?php esc_html_e( 'Menu', 'textdomain' ); ?>
	</button>

	<?php
	wp_nav_menu(
		array(
			'theme_location'       => 'primary',
			'container'            => 'nav',
			'container_id'         => 'site-navigation',
			'container_class'      => 'main-navigation',
			'container_aria_label' => __( 'Primary menu', 'textdomain' ),
			'menu_id'              => 'primary-menu',
			'menu_class'           => 'primary-menu',
			'fallback_cb'          => false,
			'depth'                => 3,
		)
	);
endif;

Rules:

• Use theme_location; do not render an arbitrary first menu by accident.
• Use fallback_cb => false unless a page-list fallback is a deliberate design decision.
• Use unique menu_id values. Duplicate IDs break toggles and accessibility.
• Use container => 'nav' plus container_aria_label for landmark clarity.
• If there is no assigned menu, render nothing or a deliberate setup/help state for administrators only.

Mobile Toggle Contract

A menu toggle is an action, so it must be a <button>, not a fake link.

Required behavior:

• type="button" so it does not submit a wrapping form.
• aria-controls points to the actual menu container or list ID.
• aria-expanded="false" initially when the menu is closed.
• JavaScript toggles both the visible state and aria-expanded.
• The menu remains usable without hover-only interactions.

Example JavaScript:

( function () {
	var button = document.querySelector( '.menu-toggle' );
	var menu = document.getElementById( 'primary-menu' );

	if ( ! button || ! menu ) {
		return;
	}

	button.addEventListener( 'click', function () {
		var expanded = button.getAttribute( 'aria-expanded' ) === 'true';

		button.setAttribute( 'aria-expanded', expanded ? 'false' : 'true' );
		menu.classList.toggle( 'is-open', ! expanded );
	} );
}() );

Enqueue this script through wp_enqueue_scripts, not inline in header.php.

Fallback Strategy

WordPress' default wp_nav_menu() fallback can output a page menu when no menu is assigned. That is often surprising in custom themes.

Use one of these explicit strategies:

• fallback_cb => false for production themes where no assigned menu should mean no menu output.
• A custom fallback callback that outputs controlled markup.
• An administrator-only notice in preview/local development, never public setup instructions for visitors.

Menu Filters

Prefer filters for small attribute/class changes.

Useful filters:

• nav_menu_css_class for <li> classes.
• nav_menu_item_id for item IDs.
• nav_menu_link_attributes for <a> attributes.
• nav_menu_submenu_css_class for submenu classes.
• nav_menu_submenu_attributes for submenu attributes.

Example:

add_filter( 'nav_menu_link_attributes', 'mytheme_nav_link_attributes', 10, 4 );

function mytheme_nav_link_attributes( $atts, $menu_item, $args, $depth ) {
	if ( 'primary' !== $args->theme_location ) {
		return $atts;
	}

	$atts['class'] = isset( $atts['class'] ) ? $atts['class'] . ' menu-link' : 'menu-link';

	return $atts;
}

Rules:

• Check theme_location before changing all menus.
• Preserve existing classes and attributes unless intentionally replacing them.
• Escape custom attribute values if they come from custom fields or options.

Custom Walkers

Avoid a custom walker unless the HTML structure must change in a way filters cannot handle.

If a walker is necessary:

• Extend Walker_Nav_Menu.
• Match the current method signatures.
• Preserve core current-menu classes and aria-current.
• Preserve core filters unless there is a deliberate reason to replace them.
• Escape every custom attribute and text value.
• Keep output deterministic and test submenu depth.
• Implement both opening and closing methods correctly.
• Review wp-includes/class-walker-nav-menu.php before changing walker output. It contains accessibility behavior that custom walkers often accidentally remove.

Review Checklist

• Menu locations are registered on after_setup_theme.
• Rendered menus use theme_location.
• Public menus do not accidentally fall back to page lists.
• container => 'nav' and container_aria_label are used for major navigation.
• IDs referenced by aria-controls exist and are unique.
• Mobile toggle is a <button> and updates aria-expanded.
• Menu JavaScript is enqueued, not hardcoded in the template.
• Filters check the intended menu location before mutating attributes.
• Custom walkers are avoided unless filters are insufficient.
• Custom walker output is escaped and preserves core accessibility state.

Common Mistakes

• Rendering wp_nav_menu() without theme_location.
• Forgetting fallback_cb => false and exposing an unwanted page list.
• Using <a href="#"> as a menu toggle.
• Creating duplicate id="primary-menu" markup in header and footer.
• Replacing all menu item classes and losing current-menu state.
• Echoing menu item custom fields without escaping.
• Writing a custom walker for a simple class or data attribute.

References

• Official documentation: https://developer.wordpress.org/themes/functionality/navigation-menus/
• Verified source paths:
  • wp-includes/nav-menu.php
  • wp-includes/nav-menu-template.php
  • wp-includes/class-walker-nav-menu.php
  • wp-content/themes/storefront/inc/structure/header.php
  • wp-content/themes/generatepress/inc/structure/navigation.php