JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li>
</ul>
<ul>
    <li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li>
</ul>
<ul>
    <li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="hr">HR</li>
    <li class="a">foo</li>
    <li class="hr">HR</li>
</ul>
<ul>
    <li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li class="hr">HR</li><li class="a">foo</li>
    <li class="b">foo</li>
    <li class="hr">HR</li>
    <li class="c">foo</li>
    <li class="a">foo</li>
    <li...

CSS

.green {color:green;}
ul {margin:10px}
li {list-style:disc;}

JavaScript

$('ul').find('li.hr:eq(4)').addClass('green');