JSFiddle - React, Tailwind, and code Playground

HTML

<ul></ul>

JavaScript

function addElement () {
var newLi = document.createElement("li");
var text = document.createTextNode("Teststring in <li>");

newLi.appendChild(text);
var ulnew = document.getElementsByTagName('ul')
ulnew[0].appendChild(newLi)    
}
addElement();