Use ajax to get the number of online users without refreshing

Client:
<Script language = "JavaScript">
<! --
VaR XMLHTTP = new activexobject ("Microsoft. XMLHTTP ");
Function sendajax ()
{
XMLHTTP. Open ("Post", "admin/usercount. aspx", true );
XMLHTTP. Send (null );
XMLHTTP. onreadystatechange = serverprocess;
}
Function serverprocess ()
{
If (XMLHTTP. readystate = 4 | XMLHTTP. readystate = 'complete ')
{
Document. getelementbyid ('elelogin'). value = XMLHTTP. responsetext;
VaR lineuser = XMLHTTP. responsetext;
VaR retstr = lineuser. Split ('<');
VaR num = retstr [0]. replace (/(^ \ s *) | (\ s * $)/g, ""); // get the expected data first because HTML is returned, then, it is added to TD, otherwise it will be deformed.
Document. getelementbyid ('onlineuser'). innertext = "online users:" + num;
}
}
Setinterval ('sendajax () ', 3000); // The total number of online queries in 10 minutes

// -->
</SCRIPT>
Server
Private void page_load (Object sender, system. eventargs E)
{
// Place user code here to initialize the page
String logined = convert. tostring (sqlhelper. executescalar (configurationsettings. deleettings ["connstring"], "getusersloginedcount"). Trim (); // The total number of logged-in users
Response. Write (logined );
}