Walker_Nav_Menu::start_lvl( string $output, int $depth, stdClass $args = null )

Starts the list before the elements are added.


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See also

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$output string Required
Used to append additional content (passed by reference).
$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

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

public function start_lvl( &$output, $depth = 0, $args = null ) {
	if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
		$t = '';
		$n = '';
	} else {
		$t = "\t";
		$n = "\n";
	$indent = str_repeat( $t, $depth );

	// Default class.
	$classes = array( 'sub-menu' );

	 * Filters the CSS class(es) applied to a menu list element.
	 * @since 4.8.0
	 * @param string[] $classes Array of the CSS classes that are applied to the menu `<ul>` element.
	 * @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_submenu_css_class', $classes, $args, $depth ) );
	$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

	$output .= "{$n}{$indent}<ul$class_names>{$n}";

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Version Description
3.0.0 Introduced.

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