JSFiddle - React, Tailwind, and code Playground

HTML

<iframe src="/echo/html/" />

JavaScript

$('iframe').load(function () {

    var $doc = $('iframe').contents();
    var $body = $('body', $doc);
    $body.append(' \
    <div id="popup"> \
        Popup! \
    </div> \
    ');
    console.log("the body where script is appended", $body[0]);
    $body.append(' \
    <script type="text/javascript"> \
        console.log("from iframe: document", document); \
        console.log("from iframe: doc.body", document.body); \
    <\/script> \
    ');

});