JSFiddle - React, Tailwind, and code Playground

HTML

<div id="ahoj"> </div>
<button id="kk"> ahoj </button>

CSS

#ahoj
{width:100px;
    height:50px;
    background-color:red;}

JavaScript

function sg()
{var x = document.getElementById("ahoj");
 var g = x.style.display;
 if(g=="none")
 {x.style.display="block"}
 else
 {x.style.display="none"};}

window.onload=ok;
function ok()
{document.getElementById("kk").onclick=sg;}