JSFiddle - React, Tailwind, and code Playground

HTML

<div id="init">
    <ul>
        <li>Hello</li>
        <li>Bye</li>
        <li class="block">
            <ol>
                <li>First</li>
                <li>Second</li>
                <li>Third</li>
            </ol>
        </li>
        <li>Test</li>
    </ul>
</div>

CSS

li { display: none; }
li.block, li.block li { display: block }

JavaScript

$("#init").find(":hidden").remove();