JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>

	<title>Parcel Sandbox</title>
	<meta charset="UTF-8">
  <link rel="manifest" href="/manifest.json">
<body>
	<div id="app">
<h1>Hello Vanilla!</h1>
<div class="havesubchild sub mpIt mpId2">

  We use the same configuration as Parcel to bundle this sandbox, you can find more
  info about Parcel 
</div>
</div>
</body>

JavaScript

// document.querySelector('.havesubchild').classList.remove('havesubchild', 'sub')

document.querySelectorAll('.havesubchild').forEach((el) => {
  el.classList.remove('havesubchild', 'sub')
})