[javascript] CORS - How do 'preflight' an httprequest?

I am trying to make a cross domain HTTP request to WCF service (that I own). I have read several techniques for working with the cross domain scripting limitations. Because my service must accommodate both GET and POST requests I cannot implement some dynamic script tag whose src is the URL of a GET request. Since I am free to make changes at the server I have begun to try to implement a workaround that involves configuring the server responses to include the "Access-Control-Allow-Origin" header and 'preflight' requests with and OPTIONS request. I got the idea from this post : Getting CORS working

At the server side, my web method is adding 'Access-Control-Allow-Origin: *' to the HTTP response. I can see that responses do include this header now. My question is: How do I 'preflight' a request (OPTIONS)? I am using jQuery.getJSON to make the GET request but the browser cancels the request right away with the infamous:

Origin http://localhost is not allowed by Access-Control-Allow-Origin

Is anyone familiar with this CORS technique? What changes need to be made at the client to preflight my request?

Thanks!

Although this thread dates back to 2014, the issue can still be current to many of us. Here is how I dealt with it in a jQuery 1.12 /PHP 5.6 context:

• jQuery sent its XHR request using only limited headers; only 'Origin' was sent.
• No preflight request was needed.
• The server only had to detect such a request, and add the "Access-Control-Allow-Origin: " . $_SERVER['HTTP_ORIGIN'] header, after detecting that this was a cross-origin XHR.

PHP Code sample:

if (!empty($_SERVER['HTTP_ORIGIN'])) {
    // Uh oh, this XHR comes from outer space...
    // Use this opportunity to filter out referers that shouldn't be allowed to see this request
    if (!preg_match('@\.partner\.domain\.net$@'))
        die("End of the road if you're not my business partner.");

    // otherwise oblige
    header("Access-Control-Allow-Origin: " . $_SERVER['HTTP_ORIGIN']);
}
else {
    // local request, no need to send a specific header for CORS
}

In particular, don't add an exit; as no preflight is needed.