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>
    <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>
</ul>

JavaScript

$(document).ready(function() {
    $('li.directory > ul').hide();
    $('li.directory > a').click(function(event) {
        $(this).parent().toggleClass('expanded');
        $(this).next().slideToggle('slow');

        event.preventDefault();
    });

});