. Net controls interact with Ajax (including datalist, gridview, etc ...)

Because the project must be created using Ajax, datalist remains in the project,
I have never known how to implement datalist as Ajax,
So I searched the internet, but I did not find it again.
Later, I used datalist and page separation in a message board that I had previously done. This idea reminds me to implement Ajax interaction by outputting the datalist control in HTML.

Code
Protected   Override   Void Render (htmltextwriter writer)
{
String SQL =   " Select count (*) from DBO. tb_message where employeeid = "   + Loginid. tostring ();
Int I _recordcount =   Int . Parse (dataaccess. getsingle (SQL, Null ). Tostring ());

If(I _recordcount> 0)
{
Writer. Write (sp. tostring ());
}
This. DB. rendercontrol (writer );
}

CodeThis method can only be used as a reference but cannot be used directly. However, this idea is to rewrite the render method.

Code
VaR S_gridview_currenpage =   ' 0 ' ;
VaR XMLHTTP;
VaR Xmlhttpget;
Function Getxmlhttpobject (){
VaR Xmlhttpnew =   Null ;
Try {
Xmlhttpnew =   New XMLHttpRequest ();
}
Catch (E ){
Try {
Xmlhttpnew =   New Activexobject ( " Msxml2.xmlhttp " );
}
Catch (E ){
Xmlhttpnew =   New Activexobject ( " Microsoft. XMLHTTP " );
}
}
Return Xmlhttpnew;
}

Function Guestbook (){
Xmlhttpget = Getxmlhttpobject ();
If (Xmlhttpget =   Null ){
Alert ( " Sorry, your browser does not support Ajax !; -) " );
Return ;
}
VaR URL =   ' Contactlist. aspx ' ;
URL = URL +   " ? SID = "   + Math. Random ();
URL = URL +   " & Page = "   + S_gridview_currenpage;
Xmlhttpget. onreadystatechange = Bookgetok;
Xmlhttpget. Open ( " Get " , URL, True );
Xmlhttpget. Send ( Null );
}
Function Bookgetok (){
If (Xmlhttpget. readystate =   4 ){
VaR Gustbookdiv = Document. getelementbyid ( " Listdiv " );
Gustbookdiv. innerhtml = Xmlhttpget. responsetext;
}
}

 
I just found that there are also corresponding server controls and JS interactions on the Internet for your reference and mutual learning.