Ajax获取json信息例子

JQuery的四中异步获取后台代码方法
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
    <script src="../Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>
    <script type="text/javascript">
        $(function () {
            $("#Getjson").click(function () {
                $.getJSON("ProceseAjaxJson.ashx", "b=3", function (date) {
                    alert(date[0].CityName);
                });
            });

            $("#GET").click(function () {
                $.get("ProceseAjaxJson.ashx", "b=4", function (date) {
                    var j = $.parseJSON(date);
                    alert(j[2].CityName);
                });
            });

            $("#Post").click(function () {
                $.post("ProceseAjaxJson.ashx", { b: 5, date: '2014' }, function (date) {
                    alert(date[0].CityName);
                },"json");
            });

            $("#Ajax").click(function () {
                $.ajax({
                url:"ProceseAjaxJson.ashx",
                data:"ss=11",
                type:"get",
                success:function(date){
                    alert(date);
                },
                error:function(date){
                    alert("出错了");
                }
                });
            });
        });
    </script>
</head>
<body>
    <input type="button" id="Getjson" value="Ajax获取Json数据" />
    <input type="button" id="GET" value="Ajax的Get请求" />
    <input type="button" id="Post" value="Ajax的Post请求" />
    <input type="button" id="Ajax" value="Ajax的请求" />
    <input type="text" id="txtjson" />
</body>
</html>
前台代码