JSFiddle - React, Tailwind, and code Playground

HTML

<div id="zalez">To tu nikdy nebylo</div>
<div id="vylez">Hello world</div>

CSS

#vylez {display:none;}

JavaScript

var e = document.getElementById("zalez");
e.style.display = "none";
var f = document.getElementById("vylez");
f.style.display = "block";