Check what control initiated AJAX Request - asp.net

Question

asp.net 2.0 / jQuery / AJAX
<script type="text/javascript">
//updated to show proper method signature
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_endRequest(hideMessage);
function hideMessage(sender, args)
{
var ctl = args.get_postBackElement();
//check if ctl is the disired control
//hide user notification message
}
</script>
i have several controls on the page that might initiate the AJAX request, but i only want my js to fire when i click one particular button. how do i check what control initiated the request so i can fire JS accordingly.
EDIT: I worked around it, but I'd still like to know if I can do it this way.
Clarification: I can't call the JS from onclick event, because the page is inside of the UpdatePanel, and i only want the JS to execute when AJAX Request ends and it was triggered by one particular button on the page. On server side, i set the myLabel.Text to some text, and then js checks if the $(myLabel.CliendID)'s innerHTML is not blank and fires the js. checking the innerHTML is my work-around since i can't figure out how to check the "sender" of AJAX Request. Hope this makes more sense now.
edit2: I've read some documentation, and turns out you CAN check the "sender" control.
Thank you.

Answer 1

This is what I am doing in my code to identify what control has initialized the request. All javascript code.
function pageLoad() {
if (!Sys.WebForms.PageRequestManager.getInstance().get_isInAsyncPostBack()) {
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(endRequestHandler);
Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(initializeRequest);
}
}
function endRequestHandler(sender, args) {
if (sender._postBackSettings.sourceElement.id == '<%= gvResults.ClientID %>') {
//do something because of this...
}
}
function initializeRequest(sender, args) {
if (CheckForSessionTimeout()) {
args.set_cancel(true);
}
else {
if (sender._postBackSettings.sourceElement.id == '<%= gvResults.ClientID %>') {
//do something because of this
}
}
}
EDITHere is the method of checking for timeout on the client side.
var sessionTimeoutDateTime = new Date();
var sessionTimeoutInterval = <%= this.SesstionTimeoutMinutes %>;
function CheckForSessionTimeout() {
var currentDateTime = new Date()
var iMiliSeconds = (currentDateTime - sessionTimeoutDateTime);
if (iMiliSeconds >= sessionTimeoutInterval) {
ShowSessionTimeout();
return true;
}
return false;
}

Answer 2

I would recommend that you do not have each control execute the same javascript function. OR, if they do, pass a parameter that indicates which one executed it.
Then, you can include your ajax in the js function that the control executes.
And, if I'm not understanding the issue correctly, perhaps you could explain it in more detail or post some code.

Answer 3

I've read some documentation, and turns out you CAN check the "sender" control. JS in the question is updated to show the proper method signature.
This article gives even better explanation.