jQuery-form-serializer

<script src="path/to/jQuery.js"></script>
<script src="path/to/jQuery-serializer.js"></script>
<script>
    $("form")
        .serializer();
        .on("serializer:data", function (e, formData) {
            alert(JSON.stringify(formData));
        })
        ;
</script>

data-field is mandatory for the fields which you want to be listed in the JSON object.

Inspect the HTML with the browser developer tools so you can see what's behind this pretty form.