title: jquery ajax unauthorized request, returns "NetworkError" and status 0
body: <p>My main goal is to understand what exactly occurs during an authorization process between a client (browser) using ajax and asp.net web api back-end.  </p>
  
  <p>So initially, I make a simple GET request to one of my controllers (allowing "Access-Control-Allow-Origin") via ajax from my browser. I take the response that I want and everything is OK so far.</p>
  
  <p>Then, I am setting an authorize attribute on the same controller on web api and I make again a simple GET request in order to study the result. So, with the help of firebug, I see that there is a "NetworkError: 401 Unauthorized - localhost/api/values". </p>
  
  <p>Besides, on the result object I see the following values: readyState : 0, responseText : "", status : 0, statusText : "error". Is this normal? Should not I see for example status : 401?
  I think I could use the accepted solution of this thread: <a href="https://stackoverflow.com/questions/12755158/unauthorized-ajax-request-succeeds">Unauthorized AJAX request succeeds</a>
  but I prefer to check a potential 401 result more strictly.</p>
  
  <p>One thought that I made is that maybe the asp.net web API by default, when you use the authorize attribute, on an unauthorized response does not include the "Access-Control-Allow-Origin" header, so I added globally a custom action filter which adds the "Access-Control-Allow-Origin" to each response, but it did not solve my problem, so I guess this is not the case.</p>