JSFiddle - React, Tailwind, and code Playground

HTML

<div id="buttoncontainer">
    <input id="button" onclick="update();" type="button" value="Update page">
</div>
<div id="tryitcontainer">
    <textarea id="codebox"></textarea>
    <iframe id="showpage"></iframe>
</div>

JavaScript

function update() {
    var codeinput = document.getElementById('codebox').value;
    $(window.frames[0].document.body).append(codeinput);
}