which is the best way to customize nav-menu-template.php?

Question

I have modified the function start_el in nav-menu-template.php substituting $item->ID with $item->title so that the html li elements in menu have a more readable class names. In detail, I have changed the line

$id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );

to

$id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->title, $item, $args );

This makes the editing of the style.css file for a theme easier. I wonder if it is possible to "transfer" the change from nav-menu-template.php to the theme (maybe functions.php?), so that I will not be forced to modify the file every time I upgrade WP version.

Answer 1

Simply add the following into your functions.php:

add_filters( 'nav_menu_item_id', 'wpse64308_nav_menu_item_id',10,3);
function wpse64308_nav_menu_item_id( $id, $item, $args){
    return 'menu-item-'.$item->title;
}