qr scanner

 const ionApp = <HTMLElement>document.getElementsByTagName('ion-app')[0];

const startScanner = () => {
            scanSub = this.qrScanner.scan().subscribe((text: string) => {
                console.log(text);
            });

            this.qrScanner.show();
            ionApp.style.display = 'none';
});

const closeScanner = () => {
            this.qrScanner.hide();
            scanSub.unsubscribe();
            ionApp.style.display = 'block';
});