ajax 返回值读取有关问题

ajax 返回值读取问题

$.ajax({

                                type: "post",

                                contentType: "application/json",

                                url: /DCSRequestName.asmx/GetName",

                                data: "{str:'" + $("#txtName").val() + "'}",

                                dataType: "json",

                                success: function (result) {

                                    $("#lstAgent").empty();

                                    if (result.d != null){                                        $.each(result.d, function (index, data) {

                                            $("#lstAgent").append("<option value='" + index + "'>" + data + "</option>");

                                            if ($("#txtName").val() == data)

                                                $("#lstAgent").val(index);

                                        });

                                        $("#lstAgent").attr("size", $("#lstAgent option").length + 1);

                                        $("#lstAgent").show();

                                    }

                                    else

                                        $("#lstAgent").hide();

                                }

                            });

服务端的webservice返回的是Dictionary<int,string> 有数据的时候返回{“d”,{....等等，}}能正常读取。当DIC……为空是返回的是{"d",{}},怎么判断result.d是否有值？if (result.d != null）不行，
你看下你接收到的数据的格式（查看http请求可以看到）
如果是string 类型，需要result=eval('(+result+)'); 转成Json格式

如果得到的是Json格式,使用
if(result.d)
{

}

就应该没有问题了
if(result.d.length>0)
{
 ....
}else{

.....
}