Mailchimp API成功消息

Im trying to create a modal popup after submitting to mailchimp. I can get the pop up to work on success but even if the form throws back a mailchimp error it stills pops up and doesn't register that it wasn't a successful send because the error came from mailchimp.

Im having trouble

Heres my script for sending the form

$('#signup').submit(function() {
    $("#message").html("Submitting your entry...");

    $.ajax({
        url: 'inc/store-address.php',
        data: $('#signup').serialize(),
        success: function(msg) {
            $('#message').html(msg);
            $('.modal').delay(500).addClass('is-visible');
        }

    });
    return false;
});

and here is the store-address.php file that sends the info to mailchimp

 <?php

 function storeAddress() {

    // Validation
    if(!$_GET['email']) { 
        return "No email address provided"; 
    } 

    if(!preg_match("/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*$/i", $_GET['email'])) {
        return "Email address is invalid"; 
    }


    require_once('MCAPI.class.php'); 

    $api = new MCAPI('api-key');

    $merge_vars = Array( 
        'EMAIL' => $_GET['email'],
        'FNAME' => $_GET['fname'], 
        'LNAME' => $_GET['lname']
        );

    $list_id = "list_id";

    if($api->listSubscribe($list_id, $_GET['email'], $merge_vars ) === true) {
        return 'Success!&nbsp;';
    } else {
        // An error ocurred, return error message   
        return '<b>Error:</b>&nbsp; ' . $api->errorMessage;
    }

}

// If being called via ajax, autorun the function
if($_GET['ajax']){ echo storeAddress(); }
?>

I will keep looking for a solution, but any help or direction much appreciated

Thanks

The request is a 200 response which is successful to the post-function, you have to check what kind of value the response actually provides to determine if it is truly a successful response. Something like this:

$.ajax({
    url: 'inc/store-address.php',
    data: $('#signup').serialize(),
    success: function(msg) {
        if(msg === 'Success! ') {
            $('#message').html(msg);
            $('.modal').delay(500).addClass('is-visible');
        }
    }

});