How to do AJAX POST cross-domain with custom headers

Question

I have been looking around all over and I cannot find a definitive answer to this.

I need to be able to perform an AJAX POST and send up custom headers. I have full

Answer 1

I don't know if you are still looking for a way to do this. This can be done. Here is a sample CORS Handler

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Api.Handlers
{
    /// 

    /// 
    /// 
    public class CorsHandler : DelegatingHandler
    {
        const string Origin = "Origin";
        const string AccessControlRequestMethod = "Access-Control-Request-Method";
        const string AccessControlRequestHeaders = "Access-Control-Request-Headers";
        const string AccessControlAllowOrigin = "Access-Control-Allow-Origin";
        const string AccessControlAllowMethods = "Access-Control-Allow-Methods";
        const string AccessControlAllowHeaders = "Access-Control-Allow-Headers";

        /// 

        /// 
        /// 
        /// 
        /// 
        /// 
        protected override Task SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            bool isCorsRequest = request.Headers.Contains(Origin);
            bool isPreflightRequest = request.Method == HttpMethod.Options;

            if (isCorsRequest)
            {
                if (isPreflightRequest)
                {
                    HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                    response.Headers.Add(AccessControlAllowOrigin, request.Headers.GetValues(Origin).First());

                    string accessControlRequestMethod = request.Headers.GetValues(AccessControlRequestMethod).FirstOrDefault();
                    if (accessControlRequestMethod != null)
                    {
                        response.Headers.Add(AccessControlAllowMethods, accessControlRequestMethod);
                    }

                    string requestedHeaders = string.Join(", ", request.Headers.GetValues(AccessControlRequestHeaders));
                    if (!string.IsNullOrEmpty(requestedHeaders))
                    {
                        response.Headers.Add(AccessControlAllowHeaders, requestedHeaders);
                    }

                    TaskCompletionSource tcs = new TaskCompletionSource();
                    tcs.SetResult(response);
                    return tcs.Task;
                }

                return base.SendAsync(request, cancellationToken).ContinueWith(t =>
                {
                    HttpResponseMessage resp = t.Result;
                    resp.Headers.Add(AccessControlAllowOrigin, request.Headers.GetValues(Origin).First());
                    return resp;
                });
            }

            return base.SendAsync(request, cancellationToken);
        }
    }
}

Once you add this, then register the handler in your Global.asax file inside the Application_Start method

GlobalConfiguration.Configuration.MessageHandlers.Add(new CorsHandler());

Now you can send your request headers. Hope that helps. This has been tested with Web API, MVC 4 and the site from Google Chrome and Firefox.