How to use push when the app is closed?

I’m using the push plugin, and work’s perfectly when the app is open, but when the app is closed the method is not called…

My code look like this:

this.platform.ready().then(() => {
  console.log('Platform ready');
  this.initPush();
}

initPush() {
  let push = Push.init({
      android: {
          senderID: "XXXXXX"
      },
      ios: {
          alert: "true",
          badge: true,
          sound: 'false'
      },
      windows: {}
  });

  push.on('registration', (data) => {
      console.log("REGISTRATION");
          localStorage.setItem('token', data.registrationId);
  });

  push.on('notification', (data) => {
      console.log('ONLY WORK'S WHEN APP IS OPEN')
  });

  push.on('error', (e) => {
      console.log(e.message);
  });

}

How can I do to show the message from my push at any moment?

Thank’s!

Ionic is just browser. You need to use OS service (background process).

My backend send the push, an this method is called, but only when the APP is open.
How I can call this method when the APP is closed?
I"m using the push plugin…
thx

as mention by xr0master. you need to use background service. this is particularly because the ionic is a web application. so the javascript file will only be triggered/fired when you open the application. hope you understand. correct me if im wrong.

How does it on Android?