错误TypeError：即使已定义google.maps.Travelmode，也未定义

Question

我正在尝试将google maps包含在我的项目中，即使一切都正确，我也遇到了上述错误。 如果我只是搜索一个位置，我会到达那里，并且一切正常，但是当我尝试显示路线时，如google docs所示，我会收到错误消息 可能是以某种方式无法识别google吗？

ngOnInit() {
    this.loadMap();
  }

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

        this.map = new google.maps.Map(
          this.mapElement.nativeElement,
          mapOptions
        );

        this.directionsRenderer.setMap(this.map);        
      })
      .catch((error) => {
        console.log("Error getting location", error);
      });
  }




calculateAndDisplayRoute() {
    this.directionsService.route(
      {
        origin: this.currentLatLng, //takes the current location
        destination: this.currentLatLng,
        waypoints: this.waypointArray,  
        optimizeWaypoints: true,
        travelMode: google.maps.Travelmode.DRIVING,//here's the problem
        drivingOptions: {
          trafficModel: "pessimistic",
        },
      },
      (response, status) => {
        if (status === "OK") {
          this.directionsRenderer.setDirections(response);
        }
      }
    );
  }