(38776) ASP.NET Core Online Shop Tutorial - Intermediate - YouTube 

When we started the Google Code project hosting service in 2006, the world of project hosting was limited. We were worried about reliability and stagnation, so we took action by giving the open source community another option to choose from. Since then, we’ve seen a wide variety of better project hosting services such as GitHub and Bitbucket bloom. Many projects moved away from Google Code to those other systems. To meet developers where they are, we ourselves migrated nearly a thousand of our own open source projects from Google Code to GitHub. 

var cors = new EnableCorsAttribute("*", "*", "*");
config.EnableCors(cors);
config.MessageHandlers.Add(new PreflightRequestsHandler());

public class PreflightRequestsHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (request.Headers.Contains("Origin") && request.Method.Method == "OPTIONS")
        {
            var response = new HttpResponseMessage {StatusCode = HttpStatusCode.OK};
            response.Headers.Add("Access-Control-Allow-Origin", "*");
            response.Headers.Add("Access-Control-Allow-Headers", "Origin, Content-Type, Accept, Authorization");
            response.Headers.Add("Access-Control-Allow-Methods", "*");
            var tsc = new TaskCompletionSource<HttpResponseMessage>();
            tsc.SetResult(response);
            return tsc.Task;
        }
        return base.SendAsync(request, cancellationToken);
    }
}

jQuery.support.cors = true;