TestLocalAction5.php

<?php

namespace Drupal\menu_test\Plugin\Menu\LocalAction;

use Drupal\Core\Menu\LocalActionDefault;
use Symfony\Component\HttpFoundation\Request;

/**
 * Defines a local action plugin with a dynamic title from user input.
 */
class TestLocalAction5 extends LocalActionDefault {
    
    /**
     * {@inheritdoc}
     */
    public function getTitle(Request $request = NULL) {
        return "<script>alert('Welcome to the jungle!')</script>";
    }

}