JSFiddle - React, Tailwind, and code Playground

HTML

<form action="" id="id_form">
    <input name="name" type="text">
    <input name="email" type="text">
    <input name="site" type="text">
    <input type="submit" value="submit">
</form>

JavaScript

$('#id_form input').on('blur', function () {
    if ($(this).val() == '') {
        $(this).css('border', '1px solid #f00');
    } else {
        $(this).css('border', '1px solid #000');
    }
});