Generates Wordpress wp_nav_menu() as a select field, for small screens

wp_nav_menu_dropdown.php

<div class="drop-down">
	<?php
	// Get the nav menu based on $menu_name (same as 'theme_location' or 'menu' arg to wp_nav_menu)
	// This code based on wp_nav_menu's code to get Menu ID from menu slug
	if ( ( $locations = get_nav_menu_locations() ) && isset( $locations[ $menu_name ] ) ) {
		$menu = wp_get_nav_menu_object( $locations[ $menu_name ] );
		$menu_items = wp_get_nav_menu_items($menu->term_id);
		$wrapper = 'select';
		
		$menu_list = '<' . $wrapper . ' id="menu-' . $menu_name . '">';
		$menu_list .= '<option value="">Go to&hellip;</option>';
		foreach ( (array) $menu_items as $key => $menu_item ) {
			$title = $menu_item->title;
			$url = $menu_item->url;
			$menu_list .= '<option value="' . $url . '">' . $title . '</option>';
		}
		$menu_list .= '</' . $wrapper . '>';
	} else {
		$menu_list = '<' . $wrapper . '><li>Menu "' . $menu_name . '" not defined.</li></' . $wrapper . '>';
	}
	// $menu_list now ready to output
	echo $menu_list;
	?>
</div>