JSFiddle - React, Tailwind, and code Playground
by kboucher
HTML
<form id="formId">
<input type="text" id="mytextbox" />
</form>
JavaScript
$(document).ready( function () {
alert( $('#formId input').hasClass('invalid') );
$('#formId input').addClass('invalid');
alert( $('#formId input').hasClass('invalid') );
});