BasicAuthenticationForXMLHttpRequests

BasicAuth1.cs

// If the request was unauthorized, add the WWW-Authenticate header 
// to the response.
private static void OnApplicationEndRequest(object sender, EventArgs e)
{
    var response = HttpContext.Current.Response;

    // see if the request sent an X-Requested-With header (Non-Browser request - 
    // used by jQuery and Angular implementations to prevent the browser from 
    // presenting the default Login dialog)
    var request = HttpContext.Current.Request;

    string authType = "Basic";

    if (response.StatusCode == 401)
    {
        if (request.Headers.AllKeys.Contains("X-Requested-With"))
        {
            if(request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                authType = "xBasic";
            }
        }

        response.Headers.Add("WWW-Authenticate",
            string.Format("{0} realm=\"{1}\"", authType, Realm));
    }
}