JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>Test</li>
    <li class="red">Test</li>
    <li>Test</li>
    <li class="red">Test</li>
</ul>

CSS

.red{ color: red }
.blue{ color: blue }

JavaScript

$(function() {
    var $lisample = $('ul').find('.red');
    
    $lisample[1].className = 'blue';
    
});