How to update marker co-ordinates in Google Map in Ionic Map using Geolocation watch?

Ionic Framework
1

I am generating a Google Map in my Ionic app, setting the center of the map to my co-ordinates using Geolocation, & adding a marker to the map (using the same co-ordinates):

All the below code is working fine at the moment:

ionViewWillEnter() {
    this.anonLogin();
    this.loadMap();
  }

  anonLogin() {
    this.afAuth.auth.signInAnonymously().then(res => {
      this.user = res.user;
      this.watch = Geolocation.watchPosition({}, (position, err) => {
        if (position) {
          this.latLng = new google.maps.LatLng(position.coords.latitude, position.coords.latitude);
          console.log('position change: ' + this.latLng);
          this.updateMarker();
        }
      });
    });
  }

  loadMap() {
    Geolocation.getCurrentPosition().then((resp) => {
      this.latLng = new google.maps.LatLng(resp.coords.latitude, resp.coords.longitude);
    }).then(() => {
      let mapOptions = {
        center: this.latLng,
        zoom: 15,
        mapTypeId: google.maps.MapTypeId.ROADMAP
      };

      var marker = new google.maps.Marker({
        position: this.latLng,
        title: "Hello World!"
      });

      this.map = new google.maps.Map(this.mapElement.nativeElement, mapOptions);
      marker.setMap(this.map);
    }).catch((err) => {
      console.log(err);
    });
  }

But when my location changes, I want the marker to move along with my location on the map also.

That is why I called this.updateMarker() above inside the Geolocation watch.

But it doesn’t look like the marker is being updated currently, here is what I have inside updateMarker() :

updateMarker() {
    var marker = new google.maps.Marker({
      position: this.latLng,
      title: "Hello World!"
    });
    marker.setMap(this.map);
  }

Can someone please tell me why my marker is not updating, & what changes are required so that it does?