JSFiddle - React, Tailwind, and code Playground

HTML

<div id="MyDiv" style="height: 20px; overflow: hidden">
  content<br>content<br>content<br>
  content<br>content<br>content<br>
  content<br>content<br>content<br>
</div>
<button type="button" onclick="GetHeight();">Get Height</button>

JavaScript

function GetHeight() {
    var oDiv = document.getElementById("MyDiv");
    var sOriginalOverflow = oDiv.style.overflow;
    var sOriginalHeight = oDiv.style.height;
    oDiv.style.overflow = "";
    oDiv.style.height = "";
    var height = oDiv.offsetHeight;
    oDiv.style.height = sOriginalHeight;
    oDiv.style.overflow = sOriginalOverflow;
    alert("Real height is " + height);
}