Mailchimp via jQuery Ajax. Submits correctly but JSON response is returned as a separate page

I have the following form:

<form class="footer-newsletter-form" id="footer-newsletter" method="post" action="http://xxxxxx.us1.list-manage.com/subscribe/post-json?u=xxxxxxxxxxxxxxxxxxxxxxxxx&id=xxxxxxxxxx&c=?">
    <input id="email" name="EMAIL" type="email" class="input-text required-entry validate-email footer__newsletter-field" value="{% if customer %}{{ customer.email }}{% endif %}" placeholder="{{ 'general.newsletter_form.email_placeholder' | t }}" aria-label="{{ 'general.newsletter_form.newsletter_email' | t }}">
    <button type="submit" title="Subscribe" class="button button1 hover-white footer__newsletter-button">SUBSCRIBE</button>
    <div id="subscribe-result"></div>
</form>

And the following jquery bit:

<script type="text/javascript">
$(document).ready(function () {
    function register($form) {
    jQuery.ajax({
        type: "GET",
        url: $form.attr('action'),
        data: $form.serialize(),
        cache       : false,
        dataType    : 'jsonp',
        contentType: "application/json; charset=utf-8",
        error       : function(err) { console.log('error') },
        success     : function(data) {
        if (data.result != "success") {
            console.log('success');
        } else {
            console.log('not success');
            //formSuccess();
        }
        }
    });
    }

    jQuery(document).on('submit', '.footer-newsletter-form', function(event) {
        try {
            var $form = jQuery(this);
            event.preventDefault();
            register($form);
        } catch(error){}
    });
});
</script>

Which submits correctly. However, when I press the submit button what I expect to happen is that the page does not refresh and when I check the browser console I'll either see "success" or "not success". Instead what happens is I'm sent to a page that displays the following JSON message: ?({"result":"success","msg":"Almost finished... We need to confirm your email address. To complete the subscription process, please click the link in the email we just sent you."}).

So how do I take that success message (or error if there's an error) and have the page not only remain as is, but also capture the success message so I can display a "Success" alert? The success alert I know how to do. I just need help having the browser remain where it is and tell the difference between success and error.

P.S. I'm not sure if this is relevant but the platform is Shopify. I don't think Shopify does anything to prevent the submission from going through as it should or the response coming back so I don't think it is relevant.