ajax获取json 格式绑定下拉框

[{"ClassID":"1","ClassName":"C#","CategorysID":"1","IsDelete":"0"},{"ClassID":"2","ClassName":"JAVA","CategorysID":"1","IsDelete":"0"},{"ClassID":"3","ClassName":"C++","CategorysID":"1","IsDelete":"0"}]

$.ajax({
                type: "post",

dataType:"json",
                async: false,
                cache: false,
                url: "/Main/GetDropList?cid=" + $("#CategoryID option:selected").attr("value"),
                success: function (data) {
                    alert(data);
                    $("#ClassedID").empty();
                    var json = eval('(' + data + ')');//转成对象
                    for (var i in json) {
                            $("#ClassedID").append("<option value='" + json[i].ClassID + "'>" + json[i].ClassName + "</option>")
                    }
                }
            })