JSFiddle - React, Tailwind, and code Playground

HTML

<div id="elem" style="position:relative; width: 100px; height: 100px; border: 1px solid black; box-sizing: padding-box">
    <div style="position: absolute; bottom: -15px;">Test</div>
</div>

JavaScript

var elem = document.getElementById("elem");

alert(elem.offsetHeight + " " + elem.getBoundingClientRect().height);
alert(elem.scrollHeight + " " + elem.getBoundingClientRect().height);