tips：使用前先引用jQuery

AjaxService.ashx — for循环DataTable组合成Json

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Web;
using Unisoft.ICM.Utility.Data;
using Unisoft.ICM.Utility.Web;

namespace ICM.Web.Home.AjaxService
{
    /// <summary>
    /// 功能：首页头部商品分类Json
    /// 作者：李志伟
    /// 时间：2016.03.22
    /// SelIndustryProductTypeData 的摘要说明
    /// </summary>
    public class SelIndustryProductTypeData : IHttpHandler//,System.Web.SessionState.IRequiresSessionState
    {
        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";

            string IndustryID = context.Request["industryid"];
            string CompanyID = context.Request["companyid"];

            string notesql = string.Format(@"select ProductTypeID,ProductTypeName from vw_Mall_Industry_ProductType where CompanyID={0} and IndustryID={1}",CompanyID,IndustryID);
            DataTable noteData = DbHelpersql.Query(notesql).Tables[0];

            string artsql = string.Format(@"select TypeID,TypeName,ParentID from tbl_Stock_ProductType where ParentID in(select distinct ProductTypeID from vw_Mall_Industry_ProductType where CompanyID={0} and IndustryID={1})",IndustryID);
            DataTable artData = DbHelpersql.Query(artsql).Tables[0];

            StringBuilder strJson = new StringBuilder();

            strJson.Append("[");
            for (int i = 0; i < noteData.Rows.Count; i++)
            {
                strJson.Append("{");
                strJson.AppendFormat("\"ProductTypeID\":\"{0}\",",noteData.Rows[i]["ProductTypeID"].ToString());
                strJson.AppendFormat("\"ProductTypeName\":\"{0}\",noteData.Rows[i]["ProductTypeName"].ToString());
                strJson.Append("\"ProData\":");
                strJson.Append("[");
                DataRow[] dtRow = artData.Select(" ParentID=" + noteData.Rows[i]["ProductTypeID"].ToString());
                for (int k = 0; k < dtRow.Count(); k++)
                {
                    strJson.Append("{");
                    strJson.AppendFormat("\"TypeID\":\"{0}\",dtRow[k]["TypeID"].ToString());
                    strJson.AppendFormat("\"TypeName\":\"{0}\"",dtRow[k]["TypeName"].ToString());

                    if (k != dtRow.Count()-1)
                        strJson.Append("},");
                    else
                        strJson.Append("}");
                }
                strJson.Append("]");
                if (i != noteData.Rows.Count - 1)
                    strJson.Append("},");
                else
                    strJson.Append("}");
            }
            strJson.Append("]");

            context.Response.Write(strJson.ToString());
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }

        /*
         结果格式如下：
         [
            {
               "ProductTypeID":"1","ProductTypeName":"时尚童鞋","ProData":[
                   { 
                        "TypeID":"1","TypeName":"轮滑鞋"     
                   },{ 
                        "TypeID":"2","TypeName":"滑雪鞋"
                   },{ 
                        "TypeID":"3","TypeName":"足球鞋"
                   }]
            },{
               "ProductTypeID":"1","ProductTypeName":"时尚男鞋","TypeName":"皮鞋"     
                   },"TypeName":"休闲鞋"
                   },"TypeName":"跑步鞋"
                   }]
            }
            //......................................
         ]
         */
    }
}

HTML — Ajax解析Json，for遍历内容

function SelIndustryProductTypeData(IndustryID,CompanyID) {
    $.ajax({
        url: '/Home/AjaxService/SelIndustryProductTypeData.ashx',type: 'GET',data: { industryid: IndustryID,companyid: CompanyID },success: function (data) {
            var dt = eval("(" + data + ")");
            var item = "";

            for (var k = 0; k <= dt.length - 1; k++) {
                item += "<dt class=\"mt15\">";
                item += "<p class=\"font14 bold\">" + dt[k].ProductTypeName + "</p>";
                item += "<span><img src=\"/images/index_iocn3_03.jpg\" width=\"12\" height=\"12\" /></span>";
                item += "</dt>";
                item += "<dd>";

                var row = dt[k].ProData.length;
                for (var j = 0; j < row; j++) {
                    item += "<a href=\"#\">" + dt[k].ProData[j].TypeName + "</a>";
                }
                item += "</dd>";
            }
            $("#nav-top").html(item);
        }
    });
}