How to use the @zxing/library.BarcodeFormat.QR_CODE function in @zxing/library

this.scanFailure = new EventEmitter();
    this.scanError = new EventEmitter();
    this.scanComplete = new EventEmitter();
    this.camerasFound = new EventEmitter();
    this.camerasNotFound = new EventEmitter();
    this.permissionResponse = new EventEmitter();
    this.hasDevices = new EventEmitter();
    this.deviceChange = new EventEmitter();

    // computed data
    this._hints = new Map();
    this.hasNavigator = typeof navigator !== 'undefined';
    this.isMediaDevicesSuported = this.hasNavigator && !!navigator.mediaDevices;

    // will start codeReader if needed.
    this.formats = [BarcodeFormat.QR_CODE];
  }

this.scanSuccess = new EventEmitter();
    this.scanFailure = new EventEmitter();
    this.scanError = new EventEmitter();
    this.scanComplete = new EventEmitter();
    this.camerasFound = new EventEmitter();
    this.camerasNotFound = new EventEmitter();
    this.permissionResponse = new EventEmitter(true);
    this.hasDevices = new EventEmitter();
    this.deviceChange = new EventEmitter();

    this._device = null;
    this._enabled = true;
    this._hints = new Map();
    this.autofocusEnabled = true;
    this.autostart = true;
    this.formats = [BarcodeFormat.QR_CODE];

    // computed data
    this.hasNavigator = typeof navigator !== 'undefined';
    this.isMediaDevicesSuported = this.hasNavigator && !!navigator.mediaDevices;
  }

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {

  availableDevices: MediaDeviceInfo[];
  currentDevice: MediaDeviceInfo = null;

  formatsEnabled: BarcodeFormat[] = [
    BarcodeFormat.CODE_128,
    BarcodeFormat.DATA_MATRIX,
    BarcodeFormat.EAN_13,
    BarcodeFormat.QR_CODE,
  ];

  hasDevices: boolean;
  hasPermission: boolean;

  qrResultString: string;

  torchEnabled = false;
  torchAvailable$ = new BehaviorSubject(false);
  tryHarder = false;

  constructor(private readonly _dialog: MatDialog) { }

  clearResult(): void {
    this.qrResultString = null;
  }