I am writing some basic tests using Content Server API v1, and encountered a problem - IE. Both 10 and 9 (most likely 8 too)
From what I understand, 9 (and 8) doesn't support XMLHTTPRequest with CORS at all, so CORS is done via XDomainRequest, which does not support custom headers. This means:
1) content type is always text, and the authentication webservice expects Content-Type: application/x-www-form-urlencoded. It simply doesn't parse raw data and complains about missing "username" argument even though it's provided
2) we won't be able to set OTCSToken header, so... everything else won't work.
As for IE 10, I cannot get it to work on Windows 8, I keep getting Access Denied on xhr.open(...), and the request isn't even sent. It works fine on Windows 7. Nevermind. The second domain was not in my trusted sites. Doh. So IE 10 is fine with XMLHttpRequest, so are Firefox and Chrome (of course).
So what about IE 9/8? Any pointers? Someone must have tested cross domain requests with IE.