This may be used to call the API on a remote site by dynamically adding
<script> tags to the document.
Note that any JSONP requests will be processed as if logged out, even if the browser session is authenticated against the remote wiki.
The MediaWiki API requires that the origin be supplied as a request parameter, appropriately named "origin", which is matched against the Origin header required by the CORS protocol. Note that this parameter must be included in any pre-flight request, and so should be included in the query string portion of the request URI even for POST requests.
To make an authenticated CORS request, the remote wiki's
$wgCrossSiteAJAXdomains setting must be set to allow the origin site.
If the CORS origin check passes, MediaWiki will include the
Access-Control-Allow-Credentials: true header in the response, so authentication cookies may be sent.
Unauthenticated CORS requests may be made from any origin by setting the "origin" request parameter to "*". In this case MediaWiki will include the
Access-Control-Allow-Credentials: false header in the response and will process the request as if logged out (in case credentials are somehow sent anyway).
When the "origin" request parameter is supplied, MediaWiki (since 1.30) will return a
MediaWiki-CORS-Rejection header with a brief failure reason if the request does not result in a successful CORS response, e.g. in case of mismatched origin or unsupported headers in a
Access-Control-Request-Headers request header.