JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>
        <a class="active" href="#"> Item </a>
        <ul>
            <li> Subitem 1 </li>
            <li> Subitem 2 </li>
        </ul>
    </li>
    <li>
        <a href="#"> Item Other</a>
    </li>
</ul>

JavaScript

$('.active').css('color','red');

$('a.active').parent().closest('ul'){
        $(this).children('li').css('color','red');
}