JSFiddle - React, Tailwind, and code Playground

HTML

<div id="Parent-div" > </div>
<div class="first-child-div"> </div>
<div class=" second-child-div"> 
    <div class="first-grand-child"> </div>
    <div class="second-grand-child"> </div>
    <div class="Third-grand-child"> 
        <div class="Grand-grand child"> 
           <button  class="Confirm-button">Confirm!</button> 
        </div>
    </div>
</div>

JavaScript

(function() {
    document.querySelector('button').addEventListener('click', function(e) {
        var text = document.createTextNode('Hello world');
        
        document.querySelector('.Grand-grand.child').appendChild(text);
    });
}());