JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
    <form id="myform" method="POST" action="test.php">
        <fieldset>
            <input type="text">
            <textarea></textarea>
            <input type="submit">
        </fieldset>
    </form>

JavaScript

$( "#myform fieldset" ).prop("disabled", true);