ASP.NET MVC2 in Action 读书笔记 [12-1] Custom Ajax

<script type="text/javascript">

        function getXmlHttpRequest() {

            var xhr;

            //check for IE implementation(s)

            if (typeof ActiveXObject != 'undefined') {

                try {

                    xhr = new ActiveXObject("Msxml2.XMLHTTP");

                } catch (e) {

                    xhr = new ActiveXObject("Microsoft.XMLHTTP");

                }

            } else if (XMLHttpRequest) {

                //this works for Firefox, Safari, Opera    

                xhr = new XMLHttpRequest();

            } else {

                alert("Sorry, your browser doesn't support ajax");

            }



            return xhr;

        }

    

        function getMessage() {

            //get our xml http request object

            var xhr = getXmlHttpRequest();



            //prepare the request

            xhr.open("GET", "get_message.html", true)

            

            //setup the callback function

            xhr.onreadystatechange = function() {

                //readyState 4 means we're done

                if(xhr.readyState != 4) return;

                    

                //populate the page with the result

                document.getElementById('result').innerHTML = xhr.responseText;

            };

        

            //fire our request

            xhr.send(null);

        }

    </script>



<button type="button" onclick="getMessage()">Get the Message</button>

<div id="result"></div>