JSFiddle - React, Tailwind, and code Playground

HTML

<iframe id="test" style="width: 400px; height: 400px;"></iframe>

JavaScript

var myIFRAME = document.getElementById("test");
var mC = myIFRAME.contentDocument,
    mCbody = mC.getElementsByTagName("body")[0];
var docE = document.createElement("div");
docE.innerHTML = "this is a test";
mCbody.appendChild(docE);