JSFiddle - React, Tailwind, and code Playground

HTML

<div class="form">
    <input type="text" /><br />
    <input type="text" />
</div>
<p class="congrats"></p>

CSS

p.congrats{display:none;}

JavaScript

$(document).ready(function() {

    $(".form input").keyup(function() {
        var emptyFields = $('.form input').filter(function() {
            return $.trim(this.value) === "";
        });

        if (!emptyFields.length) {
            alert("form has been filled");
        }
    });

});