为什么 let point 的值没有被重新分配

Question

我有一个名为 point 的变量，它会更新以保存某个位置的纬度和经度值。但是，当我在 if 函数中重新分配时，点的值不会更新。一旦进入 if 函数，point 的值就会被重新分配并打印出正确的值，但是当它离开 if 函数时，它又回到未定义状态。

generateWayPoint(address: string): string {
  let point;
  const point4 = new google.maps.LatLng(51.496144, -3.182328);

  const geocoder = new google.maps.Geocoder();
  geocoder.geocode({ 'address': address }, function (results, status) {

    if (status === google.maps.GeocoderStatus.OK) {

      point = new google.maps.LatLng(results[0].geometry.location.lat(),
                                     results[0].geometry.location.lng());
      this.wayPoint = point;
      console.log('a point in the making', this.wayPoint);
      console.log('a wayPoint in the making', this.wayPoint);

    } else {
      console.log('Geocode was not successful for the followin reason:', status);

    }
  });


  console.log('a point how it should be:', point4);
  console.log('comparing a point', point);
  console.log('comparing a wayPoint', this.wayPoint);
  return point;

}

Answer 1

这与let无关

地理编码函数被称为异步，所以在它第一次打印点时，它确实没有被赋值。

为什么 let point 的值没有被重新分配

Why is value of let point not being reassigned

javascript

angular

typescript

angular2-services