Notification in Ionic 1

ionic-v1
1

I applied code of receive notification …my code is

FCMPlugin.onNotification(function (data) {
if (data.wasTapped) {
//Notification was received on device tray and tapped by the user.
alert(JSON.stringify(data));
} else {
//Notification was received in foreground. Maybe the user needs to be notified.
alert(JSON.stringify(data));
}
});

But result is zero…I have no idea about receive notification…reffering this example