List<Person> pList = new List<Person>();
Person  p = null;
foreach(DataRow row in DataTable1.Rows){
  p = new Person();
  p.ID = Convert.ToInt32(row["ID"]);
  p.Name = row["Name"].ToString();
  pList.Add(p);
}

JavaScriptSerializer jss = new JavaScriptSerializer();
string jsonArr = jss.Serialize(pList);
context.Response.Write(jsonArr);


public class Person{
public int ID{get;set;}
public string Name{get;set;}
}

------解决方案--------------------

JScript code

$.ajax({
        url: "../Handler/TestHandler.ashx",
        async: true,
        success: function (data, status) {
            if (status == "success") {
                var json = $.parseJSON(data);
                //遍历json
            }
        }
    });