JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li class="directory"><a href="#">Parent Link</a>
        <ul>
            <li><a href="#">Sibling Link</a></li>
            <li><a href="#">Sibling Link</a></li>
            <li><a href="#">Sibling Link</a></li>
        </ul>
    </li>
</ul>
<li class="directory"><a href="#">Parent 2 Link</a>
    <ul>
        <li><a href="#">Sibling Link</a></li>
        <li><a href="#">Sibling Link</a></li>
        <li><a href="#">Sibling Link</a></li>
    </ul>
</li>

JavaScript

$(document).ready(function() {
    $('li.directory > ul').css('display', 'none');
    $('li.directory').click(function() {
        $(this).toggleClass('expanded');
        $('ul', this).slideToggle('slow');
    });

});