Here is a script which only require div tag that needs to be displayed once ajax request will be fired:
<script type="text/javascript">
// Get the instance of PageRequestManager.
var prm = Sys.WebForms.PageRequestManager.getInstance();
// Add initializeRequest and endRequest
prm.add_initializeRequest(prm_InitializeRequest);
// Called when async postback begins
function prm_InitializeRequest(sender, args) {
// get the divImage and set it to visible
var panelProg = $get('divImage');
panelProg.style.display = '';
// Disable button that caused a postback
$get(args._postBackElement.id).disabled = true;
}
</script>
<script type="text/javascript">
// Get the instance of PageRequestManager.
var prm = Sys.WebForms.PageRequestManager.getInstance();
// Add initializeRequest and endRequest
prm.add_initializeRequest(prm_InitializeRequest);
// Called when async postback begins
function prm_InitializeRequest(sender, args) {
// get the divImage and set it to visible
var panelProg = $get('divImage');
panelProg.style.display = '';
// Disable button that caused a postback
$get(args._postBackElement.id).disabled = true;
}
</script>