JSFiddle - React, Tailwind, and code Playground

HTML

<div id="parentDiv">   
  <div id="childDiv">child DIV</div>
</div>

CSS

#parentDiv { border:2px solid red; padding:5px; }
#childDiv { border:2px solid green; padding:5px; }

JavaScript

var div = document.getElementById( 'childDiv' );

div.insertAdjacentHTML( 'beforeBegin', 'my text must be added here' );