ajax取DataTable的应用

<script language="javascript" type="text/javascript">
    var flag=false;
    function AnounceShow()
    ...{
        flag=false;
        var uid=GE("Anounce_Uid").innerText;
        if(uid.length>0)
        ...{
            AnounceService.GetAnounce(uid,AnounceComplete,onFailed);
        }
    }
    function AnounceComplete(result)
    ...{        
        var o=$get("Anounce_List");
        var ss=o.innerHTML;
        if(result==null||result.rows==null)
        ...{
            window.close();
        }
        else
        ...{
                var valstr="";
                for(var i=0;i<result.rows.length;i++)
                ...{
                    valstr+=String.format("<img src='Images/Arrow1.gif' width='7' height='7' align='absmiddle'>&nbsp;<a href="javascript:WOTurnToUrl('Anounce_Menu.aspx','Anounce_Main.aspx?id={0}');">{1}</a><br>",result.rows[i].A_Id,result.rows[i].A_Title);
                }
                if(ss!=valstr)
                ...{
                    o.innerHTML=valstr;
                }
                flag=true;
                document.body.focus();
         }
    }
    function onFailed(error) ...{    
        // 取得异常信息
        var stackTrace = error.get_stackTrace();
        var message = error.get_message();
        var statusCode = error.get_statusCode();
        var exceptionType = error.get_exceptionType();
        var timeout = error.get_timedOut();
       
        // 显示异常信息
        $get("Anounce_List").innerHTML = 
            "<strong>Stack Trace: </strong>" +  stackTrace + "<br/>" +
            "<strong>Service Error: </strong>" + message + "<br/>" +
            "<strong>Status Code: </strong>" + statusCode + "<br/>" +
            "<strong>Exception Type: </strong>" + exceptionType + "<br/>" +
            "<strong>Is Timeout: </strong>" + timeout;           
        
    }
</script>
 <asp:ScriptManager ID="ScriptManager1" runat="server">
        <Services>
            <asp:ServiceReference Path="AnounceService.asmx" />
        </Services>
    </asp:ScriptManager>
    <div id="Anounce_Uid" runat="server" class="disnone"></div>
    <div class="Articletitle"><img src="Images/user.gif" width="16" height="16" hspace="2">您好！您有未查看的通知!</div>
    
    <div id="Anounce_List" class="showlist">
    </div>

AnounceService.asmx文件的后台代码如下：在类前需注明 [ScriptService]以及方法注明 [ScriptMethod]

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ScriptService]
public class AnounceService : System.Web.Services.WebService
...{
    DAL_Anounce _anounce = new DAL_Anounce();

    [WebMethod]
    [ScriptMethod]
    public DataTable GetAnounce(string uid)
    ...{
        DataTable dt = new DataTable();
        dt = _anounce.GetAnounce(uid);
        return dt;
    }

}