JSFiddle - React, Tailwind, and code Playground
HTML
<div id="hiddenParent">
<div class="childDiv">child div 1</div>
<div class="childDiv">child div 2</div>
<div class="childDiv">child div 3</div>
</div>JavaScript
var height = $(".childDiv").height();
$("#hiddenParent").hide();
alert(height);