WordPress at a glance
filter is not described

nav_menu_css_class filter-hook . WP 3.0.0

Filters the CSS class(es) applied to a menu item's list item element.

Usage

add_filter( 'nav_menu_css_class', 'filter_function_name_990', 10, 4 );
function filter_function_name_990( $classes, $item, $args, $depth ){
	// filter...

	return $classes;
}
$classes(array)
The CSS classes that are applied to the menu item's <li> element.
$item(WP_Post)
The current menu item.
$args(stdClass)
An object of wp_nav_menu() arguments.
$depth(int)
Depth of menu item. Used for padding.

Notes

  • Since 4.1.0 The $depth parameter was added.

Where the hook is called

Walker_Nav_Menu::start_el()
wp-includes/class-walker-nav-menu.php 150
$class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args, $depth ) );

Where the hook is used (in WP core)

Does not used.