WordPress at a glance
function is not described

_is_valid_nav_menu_item() WP 3.2.0

Return if a menu item is valid.

No Hooks.

Return

true/false. False if invalid, otherwise true.

Usage

_is_valid_nav_menu_item( $item );
$item(object) (required)
The menu item to check.

Code of is valid nav menu item: wp-includes/nav-menu.php WP 5.2.2

<?php
function _is_valid_nav_menu_item( $item ) {
	return empty( $item->_invalid );
}