Custom Menu Items

custom_menu_item.php

add_filter( 'wp_nav_menu_items', 'custom_menu_item', 10, 2 );
 
 function custom_menu_item ( $items, $args ) {
  if ($args->theme_location == 'primary') {
    	$items .= '<li>This is Custom Menu</li>';
	}
	return $items;
 }
 
 // custom first and last class
 function wpb_first_and_last_menu_class($items) {
    $items[1]->classes[] = 'first';
    $items[count($items)]->classes[] = 'last';
    return $items;
}
add_filter('wp_nav_menu_objects', 'wpb_first_and_last_menu_class');