asp.net 捕获throw

<script type="text/javascript">
function pageLoad() {
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);

}
function EndRequestHandler(sender, args) {
if (args.get_error() != null) {
$get("lblError").innerHTML = args.get_error().Message.toString();
args.set_errorHandled(true);

}
}
</script>