JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
<script src="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js"></script>
<script src="http://ckeditor.com/apps/ckeditor/4.3.4/ckeditor.js"></script>
  
<button type="button" data-toggle="modal" data-target="#modalAddBrand">Launch modal</button>
      
      <div class="modal fade" id="modalAddBrand" tabindex="-1" role="dialog" aria-labelledby="modalAddBrandLabel" aria-hidden="true">
      <div class="modal-dialog modal-lg">
        <div class="modal-content">
          <div class="modal-header">
            <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
            <h4 class="modal-title" id="modalAddBrandLabel">add</h4>
          </div>
          <div class="modal-body">
                <form>
                <textarea name="editor1" id="editor1" rows="10" cols="80">
                This is my textarea to be replaced with CKEditor.
                </textarea>
                </form> 
          </div>
          <div class="modal-footer">
            <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
            <button id="AddBrandButton" type="button" class="btn btn-primary">Save</button>
          </div>
        </div>
      </div>
    </div>

JavaScript

CKEDITOR.replace('editor1');