C# JSON序列化日期格式问题

          //JavaScriptSerializer js = new JavaScriptSerializer();
            IsoDateTimeConverter timeConverter = new IsoDateTimeConverter();
            //这里使用自定义日期格式，如果不使用的话，默认是ISO8601格式  
            //timeConverter.DateTimeFormat = "yyyy‘-‘MM‘-‘dd‘ ‘HH‘:‘mm‘:‘ss";
            timeConverter.DateTimeFormat = "yyyy‘-‘MM‘-‘dd";
            return JsonConvert.SerializeObject(t, Formatting.Indented, timeConverter);
        //    string result = js.Serialize(t);

//C#序列化时间转化
function ParseDate(item) {

    var timestamp = item.substring(6, 15);
    var d = new Date(timestamp * 1000);  //根据时间戳生成的时间对象
    return (d.getFullYear()) + "-" +
               (d.getMonth() + 1) + "-" +
               (d.getDate()) + " " +
               (d.getHours()) + ":" +
               (d.getMinutes()) + ":" +
               (d.getSeconds());

}
//C#序列化时间转化短日期
function ParseShortDate(item) {
    var time = (ParseDate(item)).substring(0, 9);
    return time;
}