等待 map function 完成 typescript

Question

for each 循环不会等待 map function 完成，因此 id 未定义。 我如何确保所有 id 都已映射？

getIndexes(){
 this.http.get<{data: {id: number, caption:string}[], paging: any, next: string}>(this.baseUrl +'me/media/?access_token=' + this.users + '&fields=id,caption&limit=9',
{responseType:"json"}).subscribe(response =>
  {
    const data = response.data.map(async l => {
      l.id
    })
    data.forEach(
    id => {
      this.http.get<{ media_url: string; id: string; }>(this.baseUrl + id + '/?access_token=' + this.users + '&fields=media_url').subscribe(res => {
        console.log(this.list);
        this.list.push(res.media_url);
        console.log(this.list);
        this.gallery.next(this.list);
      });
    }

  );
  }
)
}

Answer 1

尝试像这样使用等待

getIndexes(){
 this.http.get<{data: {id: number, caption:string}[], paging: any, next: string}>(this.baseUrl +'me/media/?access_token=' + this.users + '&fields=id,caption&limit=9',
{responseType:"json"}).subscribe(async response =>
  {
    const data =await response.data.map(l => {
      l.id
    })
    data.forEach(
    id => {
      this.http.get<{ media_url: string; id: string; }>(this.baseUrl + id + '/?access_token=' + this.users + '&fields=media_url').subscribe(res => {
        console.log(this.list);
        this.list.push(res.media_url);
        console.log(this.list);
        this.gallery.next(this.list);
      });
    }

  );
  }
)
}