JSFiddle - React, Tailwind, and code Playground

HTML

<div>Editable:<br>
    <iframe id="editable"></iframe>
</div>

<div>Non-editable:<br>
    <iframe id="noneditable"></iframe>
</div>

JavaScript

function writeIframe(el, editable) {
    var doc = el.contentDocument || el.contentWindow.document;
    doc.open();
    doc.write('<html><head><style type="text/css">::selection {background: pink;} ::-moz-selection {background: pink;}</style></head><body onmousedown="window.focus();)" contenteditable="' + editable + '">Select some content</body></html>');
    doc.close();
}

writeIframe(document.getElementById("editable"), true);
writeIframe(document.getElementById("noneditable"), false);