JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdn.ckeditor.com/4.5.11/standard/ckeditor.js"></script>
<form>
<textarea id="editor1" name="editor1" required></textarea>
<input type="submit">
</form>
<p></p>

CSS

.cke_editable {
  background: white;
  border: 1px solid black;
}

JavaScript

var form = document.getElementsByTagName('form')[0];
var msg = document.getElementsByTagName('p')[0];

CKEDITOR.inline('editor1');
document.getElementById('editor1').addEventListener('invalid', function () {
  msg.textContent = 'hidden textarea is invalid!';
});

form.addEventListener('submit', function (e) {
  e.preventDefault();
  msg.textContent = 'we were able to submit!';
});