JSFiddle - React, Tailwind, and code Playground

HTML

<div id="testit">
                    <div style="display: none;" class="loading">
                        My loading message
                    </div>
                    <div class="formstuff">
                        <input type="text" /><br />
                        <input type="text" /><br />
                        <input type="text" /><br />
                        <input type="text" /><br />
                        <input type="text" /><br />
                        <input type="text" /><br />
                        <input type="text" /><br />
                        <input type="button" id="showhide" />
                    </div>
                </div>

JavaScript

$(document).ready(function(){
        $("#showhide").click(function(){
            $(".formstuff").fadeOut().promise().done(function() {
                $('.loading').fadeIn();
            });
            return false;
        });
});