JSFiddle - React, Tailwind, and code Playground

HTML

<div class="foo"><div class="test">A</div></div>
<div class="bar"><div class="test">B</div></div>
<div id="toc"><div class="test">C</div></div>

JavaScript

$obj1=$('#toc');

$('.test',$obj1).css({'color': 'red'});