wp-admin/includes/menu.php:223Adds CSS classes for top-level administration menu items.
arrayOne hook fires while add_menu_classes() runs, in this order:
Filters administration menu array with classes added for top-level items.
function add_menu_classes( $menu ) { $first_item = false; $last_order = false; $items_count = count( $menu ); $i = 0; foreach ( $menu as $order => $top ) { ++$i; if ( 0 === $order ) { // Dashboard is always shown/single. $menu[0][4] = add_cssclass( 'menu-top-first', $top[4] ); $last_order = 0; continue; } if ( str_starts_with( $top[2], 'separator' ) && false !== $last_order ) { // If separator. $first_item = true; $classes = $menu[ $last_order ][4]; $menu[ $last_order ][4] = add_cssclass( 'menu-top-last', $classes ); continue; } if ( $first_item ) { $first_item = false; $classes = $menu[ $order ][4]; $menu[ $order ][4] = add_cssclass( 'menu-top-first', $classes ); } if ( $i === $items_count ) { // Last item. $classes = $menu[ $order ][4]; $menu[ $order ][4] = add_cssclass( 'menu-top-last', $classes ); } $last_order = $order; } /** * Filters administration menu array with classes added for top-level items. * * @since 2.7.0 * * @param array $menu Associative array of administration menu items. */ return apply_filters( 'add_menu_classes', $menu );}Introduced in 2.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/menu.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.