CORS support has been requested in previous related bugzilla bugs including bug 20814, bug 28700 and bug 20298.
The MediaWiki API could be used by third-party JavaScript tools a lot easier if it could return data cross-domain to Ajax users without them having to run proxies or use Flash/crossdomain.xml hacks and other such things.
The solution is simple: for HTTP GET-based, non-authenticated API requests, add the following header to the response.
Access-Control-Allow-Origin: *
More details about CORS:
http://enable-cors.org/
http://www.html5rocks.com/en/tutorials/file/xhr2/
http://www.w3.org/TR/cors/
Version: unspecified
Severity: enhancement