JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-2.2.1.min.js"></script>
<textarea name="text" id="textarea" cols="30" rows="10" maxlength="350"></textarea>
<div class="error">Please keep your message within 350 characters.</div>

CSS

.error{
  display: none;
}

JavaScript

$("textarea").keyup(function (e) {
		if($(this).val().length >=350){
			$('.error').show();
		}else{
			$('.error').hide();
		}
	});