JSFiddle - React, Tailwind, and code Playground
by Daniel Tan
HTML
<p><button>Add new item</button></p>
<ul>
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
<li>6</li>
</ul>
CSS
ul li:nth-last-child(2) { color: red; }
JavaScript
$('button').click(function() {
var n = $('ul li').length;
$('ul').append('<li>' + (n + 1) + '</li>');
});