asp.net － Microsoft AJAX Library

　　　　var webRequest = null;
        function sendRequest(action)
        {
            webRequest = new Sys.Net.WebRequest();
            webRequest.set_url("Handlers/Complex.ashx");
            webRequest.get_headers()["action"] = action;
            webRequest.set_body("data=" + encodeURIComponent("Hello World!"));
            webRequest.set_httpVerb("POST");
            webRequest.set_timeout(3000); 
            webRequest.add_completed(onCompleted);
            webRequest.invoke();
        }
        
        function onCompleted(response, eventArgs)
        {
            if (response.get_aborted())
            {
                alert("Request aborted!");
            }
            else if (response.get_responseAvailable())
            {
                var statusCode = response.get_statusCode();
                if ((statusCode < 200) || (statusCode >= 300))
                {
                    alert("Error occurred!");
                }
                else
                {
                    alert(response.get_responseData());
                    // response.get_xml();
                    // response.get_object();
                    // response.getResponseHeader(...);
                }
            }
            else if (response.get_timedOut())
            {
                alert("Request timed out!");
            }
            else
            {
                alert("Error occurred!");
            }
        }