JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <p>  element 1</p>
    <p>  element 2</p>
    <p>  element 3</p>
    <p>  element 4</p>
    <p>  element 6</p>
    <p>  element 7</p>
    <p>  element 8</p>
    <p>  element 9</p>
    <p>  element 10</p>
    <p>  element 11</p>
</div>

JavaScript

$("p:nth-child(3n+1)").css("background-color", "red");