Hardware Back Button Issue

this.platform.ready().then(() => {
this.platform.backButton.subscribeWithPriority(0, async () => {
if (this.router.url == “/login” || this.router.url == “/home” || this.router.url == “/starter”) {
let dataValue = await this.autocloseOverlaysService.trigger();
if (dataValue) {

      }
      else {
        this.showAlert();
      }

    }
    else if (this.routerOutlet.canGoBack()) {
      let dataValue = await this.autocloseOverlaysService.trigger();
      if (dataValue) {

      }
      else {
        this.navCtrl.back();
      }
    }
  });
});

}