public class MenuType
{
    public Guid Id { get; set; }
    public Guid PId { get; set; }
    public string MenuName { get; set; }
    public string Url { get; set; }
    public int OrderNum { get; set; }
    public int SonCount { get; set; }
}

protected void Page_Load(object sender, EventArgs e)
{
  if (Request["Action"] == "AJAX")
  {
    var result = GetMenu(Request["pid"]);
    JavaScriptSerializer serializer = new JavaScriptSerializer();
    string sRet = serializer.Serialize(result);
    Response.Write(sRet);
    Response.End();
  }
}

private List<MenuType> GetMenu(string pid)
{
  var result = new List<MenuType>();
  SqlConnection conn = new SqlConnection("Data Source=.;Initial Catalog=SHU;User ID=sa;Password=allen;");
  conn.Open();
  SqlCommand cmd = new SqlCommand();
  cmd.Connection = conn;
  cmd.CommandText = "select a.*,b.cout as count from Menu a left join (select COUNT(*) as cout,Menu.PId from Menu group by Menu.PId) as b on a.Id = b.PId where a.PId = '" + pid + "' order by OrderNum";
  SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
  while (dr.Read())
  {
    var obj = new MenuType();
    obj.Id =Guid.Parse(dr["Id"].ToString());
    obj.MenuName = dr["MenuName"].ToString();
    obj.OrderNum = Convert.ToInt32(dr["OrderNum"]);
    obj.PId = dr["PId"] == DBNull.Value "PId"].ToString());
    obj.Url = dr["Url"].ToString();
    obj.SonCount = dr["count"] == DBNull.Value "count"]);
    result.Add(obj);
  }
  return result;
}

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
  <link href="Scripts/themes/default/style.css" rel="stylesheet" type="text/css" />
  <script src="/UploadFiles/2021-04-02/jquery.js">

页面加载之初，先请求顶级节点
如果顶级节点的SonCount属性大于0
则使节点为闭合状态（样式为jstree-closed）
如果节点无子节点
则该节点的样式为jstree-leaf
当用户点击闭合状态的节点时，客户端发起请求
并把点击节点的ID传给后端，后端获取到点击节点的子节点后
通过append添加到点击节点下
至此，无限分级的树创建完成
其中不包含数据库
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希望本文所述对大家JavaScript程序设计有所帮助。