JSFiddle - React, Tailwind, and code Playground

HTML

<div>
  <input id="user_name" type="text">
  <span class="error_msg">Name is required.</span>
</div>

<div>
  <input id="user_email" type="text">
  <span class="error_msg">Email is required.</span>
</div>

<div>    
  <input id="message_subject" type="text">
  <span class="error_msg">Message subject is required.</span>
</div>      
    
<div>
  <textarea id="message_body"></textarea>
  <span class="error_msg">A message is required.</span>
</div>

CSS

.error_msg {
  display: none;
}

div.error .error_msg {
  display: inline;
}

JavaScript

$('input, textarea').change(function() {
  $(this).parent('div').toggleClass('error', !$(this).val());
}).change();