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

Starts the list before the elements are added.

Description

Parameters

$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.

Default value: null

Source

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

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 = join( ' ', 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}";
	}

Uses

Uses	Description
wp-includes/class-walker-nav-menu.php: nav_menu_submenu_css_class	Filters the CSS class(es) applied to a menu list element.
wp-includes/formatting.php: esc_attr()	Escaping for HTML attributes.
wp-includes/plugin.php: apply_filters()	Calls the callback functions that have been added to a filter hook.

Changelog

Version	Description
3.0.0	Introduced.

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Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/classes/walker_nav_menu/start_lvl