Starts the element output.

• Walker::start_el()

$output string Required

Used to append additional content (passed by reference).

$data_object WP_Post Required

Menu item data object.

$depth int Required

Depth of menu item. Used for padding.

$args stdClass Optional

An object of wp_nav_menu() arguments.

More Arguments from wp_nav_menu( ... $args )

Array of nav menu arguments.

• menuint|string|WP_Term
  Desired menu. Accepts a menu ID, slug, name, or object.
  
• menu_classstring
  CSS class to use for the ul element which forms the menu.
  Default 'menu'.
• menu_idstring
  The ID that is applied to the ul element which forms the menu.
  Default is the menu slug, incremented.
• containerstring
  Whether to wrap the ul, and what to wrap it with.
  Default 'div'.
• container_classstring
  Class that is applied to the container.
  Default 'menu-{menu slug}-container'.
• container_idstring
  The ID that is applied to the container.
• container_aria_labelstring
  The aria-label attribute that is applied to the container when it's a nav element.
• fallback_cbcallable|false
  If the menu doesn't exist, a callback function will fire.
  Default is 'wp_page_menu'. Set to false for no fallback.
• beforestring
  Text before the link markup.
• afterstring
  Text after the link markup.
• link_beforestring
  Text before the link text.
• link_afterstring
  Text after the link text.
• echobool
  Whether to echo the menu or return it. Default true.
• depthint
  How many levels of the hierarchy are to be included.
  0 means all. Default 0.
  Default 0.
• walkerobject
  Instance of a custom walker class.
• theme_locationstring
  Theme location to be used. Must be registered with register_nav_menu() in order to be selectable by the user.
• items_wrapstring
  How the list items should be wrapped. Uses printf() format with numbered placeholders. Default is a ul with an id and class.
• item_spacingstring
  Whether to preserve whitespace within the menu's HTML.
  Accepts 'preserve' or 'discard'. Default 'preserve'.

Default: null

$current_object_id int Optional

ID of the current menu item. Default 0.

File: wp-includes/class-walker-nav-menu.php. View all references

public function start_el( &$output, $data_object, $depth = 0, $args = null, $current_object_id = 0 ) {
	// Restores the more descriptive, specific name for use within this method.
	$menu_item = $data_object;

	if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
		$t = '';
		$n = '';
	} else {
		$t = "\t";
		$n = "\n";
	}
	$indent = ( $depth ) ? str_repeat( $t, $depth ) : '';

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

	/**
	 * Filters the arguments for a single nav menu item.
	 *
	 * @since 4.4.0
	 *
	 * @param stdClass $args      An object of wp_nav_menu() arguments.
	 * @param WP_Post  $menu_item Menu item data object.
	 * @param int      $depth     Depth of menu item. Used for padding.
	 */
	$args = apply_filters( 'nav_menu_item_args', $args, $menu_item, $depth );

	/**
	 * Filters the CSS classes applied to a menu item's list item element.
	 *
	 * @since 3.0.0
	 * @since 4.1.0 The `$depth` parameter was added.
	 *
	 * @param string[] $classes   Array of the CSS classes that are applied to the menu item's `<li>` element.
	 * @param WP_Post  $menu_item The current menu item object.
	 * @param stdClass $args      An object of wp_nav_menu() arguments.
	 * @param int      $depth     Depth of menu item. Used for padding.
	 */
	$class_names = implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $menu_item, $args, $depth ) );
	$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

	/**
	 * Filters the ID attribute applied to a menu item's list item element.
	 *
	 * @since 3.0.1
	 * @since 4.1.0 The `$depth` parameter was added.
	 *
	 * @param string   $menu_item_id The ID attribute applied to the menu item's `<li>` element.
	 * @param WP_Post  $menu_item    The current menu item.
	 * @param stdClass $args         An object of wp_nav_menu() arguments.
	 * @param int      $depth        Depth of menu item. Used for padding.
	 */
	$id = apply_filters( 'nav_menu_item_id', 'menu-item-' . $menu_item->ID, $menu_item, $args, $depth );
	$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';

	$output .= $indent . '<li' . $id . $class_names . '>';

	$atts           = array();
	$atts['title']  = ! empty( $menu_item->attr_title ) ? $menu_item->attr_title : '';
	$atts['target'] = ! empty( $menu_item->target ) ? $menu_item->target : '';
	if ( '_blank' === $menu_item->target && empty( $menu_item->xfn ) ) {
		$atts['rel'] = 'noopener';
	} else {
		$atts['rel'] = $menu_item->xfn;
	}
	$atts['href']         = ! empty( $menu_item->url ) ? $menu_item->url : '';
	$atts['aria-current'] = $menu_item->current ? 'page' : '';

	/**
	 * Filters the HTML attributes applied to a menu item's anchor element.
	 *
	 * @since 3.6.0
	 * @since 4.1.0 The `$depth` parameter was added.
	 *
	 * @param array $atts {
	 *     The HTML attributes applied to the menu item's `<a>` element, empty strings are ignored.
	 *
	 *     @type string $title        Title attribute.
	 *     @type string $target       Target attribute.
	 *     @type string $rel          The rel attribute.
	 *     @type string $href         The href attribute.
	 *     @type string $aria-current The aria-current attribute.
	 * }
	 * @param WP_Post  $menu_item The current menu item object.
	 * @param stdClass $args      An object of wp_nav_menu() arguments.
	 * @param int      $depth     Depth of menu item. Used for padding.
	 */
	$atts = apply_filters( 'nav_menu_link_attributes', $atts, $menu_item, $args, $depth );

	$attributes = '';
	foreach ( $atts as $attr => $value ) {
		if ( is_scalar( $value ) && '' !== $value && false !== $value ) {
			$value       = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
			$attributes .= ' ' . $attr . '="' . $value . '"';
		}
	}

	/** This filter is documented in wp-includes/post-template.php */
	$title = apply_filters( 'the_title', $menu_item->title, $menu_item->ID );

	/**
	 * Filters a menu item's title.
	 *
	 * @since 4.4.0
	 *
	 * @param string   $title     The menu item's title.
	 * @param WP_Post  $menu_item The current menu item object.
	 * @param stdClass $args      An object of wp_nav_menu() arguments.
	 * @param int      $depth     Depth of menu item. Used for padding.
	 */
	$title = apply_filters( 'nav_menu_item_title', $title, $menu_item, $args, $depth );

	$item_output  = $args->before;
	$item_output .= '<a' . $attributes . '>';
	$item_output .= $args->link_before . $title . $args->link_after;
	$item_output .= '</a>';
	$item_output .= $args->after;

	/**
	 * Filters a menu item's starting output.
	 *
	 * The menu item's starting output only includes `$args->before`, the opening `<a>`,
	 * the menu item's title, the closing `</a>`, and `$args->after`. Currently, there is
	 * no filter for modifying the opening and closing `<li>` for a menu item.
	 *
	 * @since 3.0.0
	 *
	 * @param string   $item_output The menu item's starting HTML output.
	 * @param WP_Post  $menu_item   Menu item data object.
	 * @param int      $depth       Depth of menu item. Used for padding.
	 * @param stdClass $args        An object of wp_nav_menu() arguments.
	 */
	$output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $menu_item, $depth, $args );
}