我正在使用打字稿,试图获取我们当前所在位置的地理位置。我可以获得位置,但是我的代码继续运行而没有设置位置。我决定使用等待和承诺。我创建了一个服务,如下所示:
@Injectable()
export class GoogleMapsService {
private latitude: number;
private longitude:number;
public currentLongitude(): number {
return this.longitude;
}
public currentLatitude(): number {
return this.latitude;
}
constructor() {
this.setCurrentLocation();
}
private async setCurrentLocation() {
let location: GoogleLocation = await this.getLocation();
this.latitude = location.latitude;
this.longitude = location.longitude;
}
private getLocation(): Promise<GoogleLocation> {
let promise = new Promise<GoogleLocation>(() => {
let location = new GoogleLocation();
navigator.geolocation.getCurrentPosition(position => {
location.latitude = position.coords.latitude;
location.longitude = position.coords.longitude;
});
return location;
});
return promise;
}
}
所以我的问题是我等待时如何设置它。所以当我尝试访问它时?
您永远不会在中解决您的承诺getLocation
,因此自然await
会永远等待。从promise执行器(您传递给的函数new Promise
)中返回值并不能解决promise,请注意,您要返回的内容返回的时间太早,无法在其上填写坐标。
相反,在您的Promise执行程序函数中接受resolve
和reject
参数并使用它们:
private getLocation(): Promise<GoogleLocation> {
return new Promise<GoogleLocation>((resolve, reject) => {
navigator.geolocation.getCurrentPosition(position => {
if (/*...it didn't work...*/) {
reject(new Error(/*...*/));
} else {
// It worked
const location = new GoogleLocation();
location.latitude = position.coords.latitude;
location.longitude = position.coords.longitude;
resolve(location);
// Maybe you could just `resolve(position.coords)`?
}
});
});
}
旁注:如果您承诺了地理位置服务,则根本不需要new Promise
那里。
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