JSFiddle - React, Tailwind, and code Playground

HTML

<form id="bcscan" action="" method="post">
    <input type="text" />
    <input type="text" />
    <input type="text" />
    <button type="submit">Submit</button>
</form>

CSS

.warning {
    background: red;
}

JavaScript

$(document).ready(function () {      
    $("#bcscan").submit(function (e) {
        e.preventDefault();
        
        var invalidCount = $('input').filter(function() {
            return ($(this).val() === ' ');
        }).addClass('warning').length;
        
        if (invalidCount == 0) {
            alert('valid');
        }
    });

});