public doRequestCameraPermission() {
   this.barcodeScanner.requestCameraPermission().then(
       function () {
         console.log("Camera permission requested");
       }
   );
 }

 private scan(front: boolean, flip: boolean, torch?: boolean, orientation?: string) {
   this.barcodeScanner.scan({
     cancelLabel: "EXIT. Also, try the volume buttons!", // iOS only, default 'Close'
     cancelLabelBackgroundColor: "#333333", // iOS only, default '#000000' (black)
     message: "Use the volume buttons for extra light", // Android only, default is 'Place a barcode inside the viewfinder rectangle to scan it.'
     preferFrontCamera: front,     // Android only, default false
     showFlipCameraButton: flip,   // default false
     showTorchButton: torch,       // iOS only, default false
     torchOn: false,               // launch with the flashlight on (default false)
     resultDisplayDuration: 500,   // Android only, default 1500 (ms), set to 0 to disable echoing the scanned text
     orientation: orientation,     // Android only, default undefined (sensor-driven orientation), other options: portrait|landscape
     beepOnScan: true,             // Play or Suppress beep on scan (default true)
     openSettingsIfPermissionWasPreviouslyDenied: true, // On iOS you can send the user to the settings app if access was previously denied
     closeCallback: () => {
       console.log("Scanner closed @ " + new Date().getTime());
     }
   }).then(
       function (result) {
         console.log("--- scanned: " + result.text);
         // Note that this Promise is never invoked when a 'continuousScanCallback' function is provided
         setTimeout(function () {
           // if this alert doesn't show up please upgrade to {N} 2.4.0+
           alert({
             title: "Scan result",
             message: "Format: " + result.format + ",\nValue: " + result.text,
             okButtonText: "OK"
           });
         }, 500);
       },
       function (errorMessage) {
         console.log("No scan. " + errorMessage);
       }
   );
 }

 public doContinuousScan() {
   this.barcodeScanner.scan({
     reportDuplicates: true,
     continuousScanCallback: function (result) {
       console.log(`${result.format}: ${result.text} @ ${new Date().getTime()}`);
     },
     closeCallback: () => {
       console.log("Scanner closed @ " + new Date().getTime());
     }
   });
 }

 public doCheckHasCameraPermission() {
   this.barcodeScanner.hasCameraPermission().then(permitted => {
     alert({
       title: "Has Camera permission?",
       message: permitted ? "YES" : "NO",
       okButtonText: "OK"
     });
   }, (err) => {
     alert(err);
   });
 }

 public doCheckAvailable() {
   this.barcodeScanner.available().then(avail => {
     alert({
       title: "Scanning available?",
       message: avail ? "YES" : "NO",
       okButtonText: "OK"
     });
   }, (err) => {
     alert(err);
   });
 }

 let scan = () => {
   this.barcodeScanner.scan({
     formats: "QR_CODE, EAN_13",
     beepOnScan: true,
     reportDuplicates: true,
     preferFrontCamera: false
     // continuousScanCallback: scanResult => {
     //   console.log("result: " + JSON.stringify(scanResult));
     //   this.barcodeScanner.stop();
     // }
   })
       .then(result => console.log(JSON.stringify(result)))
       .catch(error => console.log(error));
 };

  public scanTapped(): void {
    let scan = () => {
      this.barcodeScanner.scan({
        formats: "QR_CODE, EAN_13",
        beepOnScan: true,
        reportDuplicates: true,
        preferFrontCamera: false
        // continuousScanCallback: scanResult => {
        //   console.log("result: " + JSON.stringify(scanResult));
        //   this.barcodeScanner.stop();
        // }
      })
          .then(result => console.log(JSON.stringify(result)))
          .catch(error => console.log(error));
    };

    this.barcodeScanner.hasCameraPermission()
        .then(granted => granted ? scan() : console.log("Permission denied"))
        .catch(() => {
          this.barcodeScanner.requestCameraPermission()
              .then(() => scan());
        });
  }

 public doContinuousScanMax3() {
   let count = 0;
   let self = this;
   this.barcodeScanner.scan({
     reportDuplicates: false,
     closeCallback: () => {
       console.log("Scanner closed @ " + new Date().getTime());
     },
     continuousScanCallback: function (result) {
       count++;
       console.log(result.format + ": " + result.text + " (count: " + count + ")");
       if (count === 3) {
         self.barcodeScanner.stop();
         setTimeout(function () {
           alert({
             title: "Scanned 3 codes",
             message: "Check the log for the results",
             okButtonText: "Sweet!"
           });
         }, 1000);
       }
     }
   });
 }

 .catch(() => {
   this.barcodeScanner.requestCameraPermission()
       .then(() => scan());
 });