JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="nav">
    <li class="program"><a href="#">Program</a></li>
    <div class="secondNav">
        <ul>
            <li><a href="#">Teknik</a></li>
            <li><a href="#">Naturvetenskap</a></li>
            <li><a href="#">El</a></li>
        </ul>
    </div>
    <li><a href="#">Nösnäs</a></li>
    <li><a href="#">Schema</a></li>
    <li><a href="#">Matsal</a></li>
</ul>

JavaScript

$('li.program').on('click', function() {
    $('.secondNav').toggle();
});