JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper" style="height:100px">
    <p>Inner stuff.</p>
</div>

CSS

div {
    width: 100px;
    height: 100px;
    background: gray;
    overflow: auto;
    padding: 5px;
}

p {
    width:200px;
    background: red;
}

JavaScript

var wrapEl = document.getElementById('wrapper');

wrapEl.addEventListener('scroll', function(e) {
    console.log(
        wrapEl.offsetHeight, 
        wrapEl.clientHeight,
        wrapEl.style.height);
});