AJAX calls to IDN don't work in IE and Opera

[SergeyBiryukov]

In jQuery 1.5+, AJAX requests on sites with IDN domains don't work in IE 8 or 9.

On Edit Post screen, adding a new category results in JS error:

Message: 'parsed.responses' - is null or not an object
Line: 311
Char: 4
Code: 0
URI: http://домен.рф/wp-admin/js/post.dev.js?ver=20110524

On Categories screen, adding a new category silently fails.

According to ​jaubourg's comment in jQuery bug tracker, the request is considered cross-domain and, since IE doesn't support cross-domain requests, AJAX won't find a suitable transport and bail out. The ticket only refers to IE 8, but I've checked this in IE 9, and it seems to show the same behaviour.

A workaround suggested there is to use unencoded domain name or strip it completely.

Attached a workaround plugin.

Opera 11.51 is also affected.

18952.patch​ and 18952.2.patch​ are two different attempts to use a relative admin URL for AJAX requests.

Related: ticket:10690:18.

Well, relative_admin_url() from 18952.patch​ obviously doesn't need $scheme parameter.

Perhaps this should be wp_ajax_url() instead of a wrapper, as we probably wouldn't use it elsewhere.

Replying to nacin:

Perhaps this should be wp_ajax_url() instead of a wrapper, as we probably wouldn't use it elsewhere.

Thanks, done in 18952.3.patch​.

I was thinking all of the url functions that accept a scheme argument could accept relative and root_relative, or the like. No new function needed unless we want a convenience wrapper or filters with more specific context.

Replying to ryan:

I was thinking all of the url functions that accept a scheme argument could accept relative and root_relative, or the like.

Makes sense, done in 18952.4.patch​. 18952.5.patch​ also updates PHPDocs.

In [19870]:

Introduce 'relative' scheme to return only the paths for home_url, site, admin, network_, and get_ variants. props SergeyBiryukov, see #18952.

In [19871]:

Use relative paths for admin-ajax.php to avoid cross-domain issues with IDN domains in IE and Opera. props SergeyBiryukov, fixes #18952.

In [20188]:

URL to admin-ajax.php should be relative. see #19910. see #18952.

In [20191]:

Use ajaxurl rather than direct references to admin-ajax.php. see #18952.