Hardware back button doesn't the app on Android with Ionic 4

Question

I am facing problem with the hardware back button on android. I am working with Ionic CLI 4.12.0 I want to exit the app when user on homePage and clicks back button. But back button event is not firing up. It navigate to login page then restarts the app. I am using Tabs template in my app. I have tried many answers of stackoverflow that claims solution to the similar problem. I have setup code in app component as following:

@ViewChild(IonRouterOutlet) routerOutlet: IonRouterOutlet;

  constructor(private platform: Platform){
      this.platform.backButton.subscribeWithPriority(0, () => {
      console.log("back button clicked");
      navigator["app"].exitApp();
})
}

Answer 1

Finally I found the answer of my question:

  ionViewDidEnter() {
    document.addEventListener("backbutton",function(e) {
      console.log("disable back button called from tab 1")
    }, false);
}