JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
<script src="https://cdn.ckeditor.com/4.5.11/standard/ckeditor.js"></script>


<textarea name="editor1" id="editor1" rows="10" cols="80">
This is my textarea to be replaced with CKEditor.
</textarea>
<br />
<input name="file" type="file" id="files" class="form-control" value="">

JavaScript

CKEDITOR.replace( 'editor1' );

$(document).ready(function() {
function readTextFile(file, callback, encoding) {
			var reader = new FileReader();
			reader.addEventListener('load', function (e) {
				callback(this.result);
			});
			if (encoding) reader.readAsText(file, encoding);
			else reader.readAsText(file);
		}

		function fileChosen(input, output) {
			if ( input.files && input.files[0] ) {
				readTextFile(
					input.files[0],
					function (str) {
              output.setData(str);
              output.updateElement();
					}
				);
			}
		}

		$('#files').on('change', function () {
		var result = $("#files").text();
			fileChosen(this, CKEDITOR.instances.editor1);
		});
    });