JSFiddle - React, Tailwind, and code Playground

HTML

<div style="height: 2200px;"></div>

<!-- All you care for is this iframe below, the rest is just to fill up the page. -->
<iframe id="bar" style="height: 300px;"></iframe>

<div style="height: 2200px;"></div>

JavaScript

var iframeBody = document.getElementById('bar').contentWindow.document.body;

iframeBody.innerHTML = '<p>Try to select some text</p> <div style="height: 1000px;"></div>';

// For your convenience, auto scroll the outer window to the iframe.
window.scrollTo(0, 2150);