Really basic method for calculating if a request is an ajax/data request

OwinRequestExt.cs

using System;

namespace Microsoft.Owin {

	public static class OwinRequestExt {

		/// <summary>
		/// Really basic method for calculating if a request is an ajax/data request
		/// </summary>
		public static bool IsAjaxRequest(this IOwinRequest request) {

			if (request == null) {
				throw new ArgumentNullException("request");
			}

			IHeaderDictionary headers = request.Headers;

			if (headers != null) {

				var contentType = headers["Content-Type"];

				if (contentType != null) {

					var ct = contentType.ToLowerInvariant();

					return (ct == "application/json" || ct == "text/json" || ct == "application/xml" || ct == "text/xml" || headers["X-Requested-With"] == "XMLHttpRequest");
				}

			}

			return false;
		}
	}
}