jamesvl

Resolved

The AJAX request was failing on IE because my WP site had its admin_ssl turned on.

A visitor on the site using http would be given the MailChimp form and the AJAX call would go to the https version of the site.

That cross-domain request (from http or https, even on the same domain) works in FF and Chrome, but fails in IE8 and IE9. (May not be an issue in IE10.)

The Fix

I had to adjust the call to admin_url() in the main plugin file, based on the server’s port.

This will let the script work on both http and https versions of the site, and falls back to the old behavior if you’re running on a non-standard port.

if(!defined('YKSEME_URL_WP_AJAX')) {
   if ($_SERVER['SERVER_PORT'] == 80)
       define('YKSEME_URL_WP_AJAX', admin_url('admin-ajax.php', 'http'));
   else if ($_SERVER['SERVER_PORT'] == 443)
      define('YKSEME_URL_WP_AJAX', admin_url('admin-ajax.php', 'https'));
   else
      define('YKSEME_URL_WP_AJAX', admin_url('admin-ajax.php'));
}