JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<body>
	<h1>Heading</h1>
	<button onclick="measure()">Measure</button>
	<script type="text/javascript">
		function measure() {
			alert(
      "document.body.scrollHeight: " + document.body.scrollHeight +
      "\ndocument.documentElement.scrollHeight: " + document.documentElement.scrollHeight +
      "\ndocument.documentElement.getBoundingClientRect().height: " + document.documentElement.getBoundingClientRect().height);
		}
	</script>
</body>
</html>