JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="menu">
    <li><a href="#">Event Overview</a>
        <ul class="sub-menu">
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
        </ul>
    </li>
    <li><a href="#">About</a>
        <ul class="sub-menu">
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
        </ul>
    </li>

    <li><a href="#">Blog</a>
        <ul class="sub-menu">
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
        </ul>
    </li>

    <li><a href="#">Contact</a>
        <ul class="sub-menu">
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
            <li><a href="#">Some Text Here</a></li>
        </ul>
    </li>

</ul>

CSS

.active { color:red }

JavaScript

$(function() {
    $('.sub-menu').each(function() {
        $('li:last a', this).addClass('active');
    });
});