Add top level menu item title to start_lvl in Wordpress menu walker

Question

I've created a custom WordPress menu using the WordPress walker function. I've managed to do all the necessary HTML I need except adding the top-level menu title to just after one of the divs in the "start_lvl" section in the function.

Output should look like this:

<ul>
  <li><a href="#">Title</a>
    <div class="mega-menu">
     <div class="mega-menu-inner">
       <h2 class="fz-40">DISPLAY TOP MENU TITLE HERE</h2>
         <ul class="mega-menu-accordion-wrap">
             <li class="mega-menu-accordion">
                 <a href="#"></a>
                 <div class="mega-menu-accordion-inner">
                    <ul>
                      <li><a href="#"></a>
                        <div class="sub-mega-menu-wrap">
                          <ul>
                            <li><a href="#"></a></li>
                          </ul>
                        </div>
                       </li>
                    </ul> 
                  </div>
              </li>
           </ul> 
         </div>
      </div>
    </li>
 </ul>

This is what I have so far for the WP nav walker:

wp_nav_menu( array( 
    'theme_location'    => "header-menu", 
    'walker' => new WPDocs_Walker_Nav_Menu() ) ); 

/**
 * Custom walker class.
 */

class WPDocs_Walker_Nav_Menu extends Walker_Nav_Menu {


/**
 * Starts the list before the elements are added.
 *
 * Adds classes to the unordered list sub-menus.
 *
 * @param string $output Passed by reference. Used to append additional content.
 * @param int    $depth  Depth of menu item. Used for padding.
 * @param array  $args   An array of arguments. @see wp_nav_menu()
 */
function start_lvl( &$output, $depth = 0, $args = array() ) {

    // Depth-dependent classes.
    $indent = ( $depth > 0  ? str_repeat( "\t", $depth ) : '' ); // code indent
    $display_depth = ( $depth + 1); // because it counts the first submenu as 0
    $classes = array(
        'sub-menu',
        ( $display_depth % 2 == 0  ? 'menu-odd' : 'mega-menu-accordion-wrap' ),
        ( $display_depth >=2 ? 'sub-sub-menu' : '' ),
        'menu-depth-' . $display_depth
    );
    $class_names = implode( ' ', $classes );
    
    // Build HTML for output.
    if( $display_depth === 1):
        global $title;
        $output .= '<div class="mega-menu">';
        $output .= '<div class="mega-menu-container-wrap">';
        $output .= '<div class="mega-menu-help-bar"><figure> <img src="'.get_template_directory_uri().'/svg/search-white.svg" alt=""></figure><a href="#">Need some help?</a></div>';
        $output .= '<div class="mega-menu-inner">';
        $output .= '<h2 class="fz-40">Need the Title Here''</h2>';
        $output .= "\n" . $indent . '<ul class="' . $class_names . '">' . "\n";
    elseif( $display_depth % 3 === 0):
        $output .= "\n" . $indent . '<div class="sub-mega-menu-wrap">' . "\n";
        $output .= "\n" . $indent . '<ul class="' . $class_names . '">' . "\n";

    elseif( $display_depth % 2 === 0):
        $output .= "\n" . $indent . '<div class="mega-menu-accordion-inner">' . "\n";
        $output .= "\n" . $indent . '<ul class="' . $class_names . '">' . "\n";
    else:
        $output .= "\n" . $indent . '<ul class="' . $class_names . '">' . "\n";
    endif;
}

/**
 * Start the element output.
 *
 * Adds main/sub-classes to the list items and links.
 *
 * @param string $output Passed by reference. Used to append additional content.
 * @param object $item   Menu item data object.
 * @param int    $depth  Depth of menu item. Used for padding.
 * @param array  $args   An array of arguments. @see wp_nav_menu()
 * @param int    $id     Current item ID.
 */
function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
    global $wp_query;
    $indent = ( $depth > 0 ? str_repeat( "\t", $depth ) : '' ); // code indent

    // Depth-dependent classes.
    $depth_classes = array(
        ( $depth == 0 ? 'main-menu-item' : 'sub-menu-item' ),
        ( $depth >=2 ? 'sub-sub-menu-item' : '' ),
        ( $depth % 2 == 0 ? 'menu-item-odd' : 'mega-menu-accordion' ),
        'menu-item-depth-' . $depth
    );
    $depth_class_names = esc_attr( implode( ' ', $depth_classes ) );

    // Passed classes.
    $classes = empty( $item->classes ) ? array() : (array) $item->classes;
    $class_names = esc_attr( implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) ) );

    // Build HTML.
    
    if( $depth % 2 === 0):
        $output .= $indent . '<li id="nav-menu-item-'. $item->ID . '" class="' . $depth_class_names . ' ' . $class_names . ' ">';
    else:
        $output .= $indent . '<li id="nav-menu-item-'. $item->ID . '" class="' . $depth_class_names . ' ' . $class_names . '">';
    endif;

    // Link attributes.
    $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
    $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
    $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
    $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';
    $attributes .= ' class="menu-link ' . ( $depth > 0 ? 'sub-menu-link' : 'main-menu-link' ) . '"';

    // Build HTML output and pass through the proper filter.
    $item_output = sprintf( '%1$s<a%2$s>%3$s%4$s%5$s</a>%6$s',
        $args->before,
        $attributes,
        $args->link_before,
        apply_filters( 'the_title', $item->title, $item->ID ),
        $args->link_after,
        $args->after
    );
    $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
}

}

Answer 1

Solved this shortly after my post, for anyone who requires this, I did the following:

Add this to the functions.php file:

function add_menu_title( $item_output, $item, $depth, $args ) {
    global $menuTitle;
    $menuTitle = $item->title;
    return $item_output;
}
add_filter( 'walker_nav_menu_start_el', 'add_menu_title', 10, 4);

Then in your header template just add this to the section you would like it display. In my example I updated the depth===1 to the following:

if( $display_depth === 1):
            global $menuTitle;
            $output .= '<div class="mega-menu">';
            $output .= '<div class="mega-menu-container-wrap">';
            $output .= '<div class="mega-menu-help-bar"><figure> <img src="'.get_template_directory_uri().'/svg/search-white.svg" alt=""></figure><a href="#">Need some help?</a></div>';
            $output .= '<div class="mega-menu-inner">';
            $output .= '<h2 class="fz-40">'.$menuTitle.'</h2>';
            $output .= "\n" . $indent . '<ul class="' . $class_names . '">' . "\n";