地图的结果是NaN

Question

我的模拟服务中具有以下数据结构，并且由于映射的结果，在完成以下链后，我收到NaN，但是服务中的值为数字。

我在做什么错了？

{
  "person": [{
    "val1": 1,
    "val2": 2
  }],
  "facility": [{
    "val3": 3,
    "val4": 4
  }],
  "exposure": [{
    "val5": 5
  }]
}

我试图获取响应结果的组件：

import { Injectable } from '@angular/core';
import { Person } from './entities/person';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';

@Injectable()
export class DataService {

  apiUrl1: string = 'http://localhost:3000/person/?';
  apiUrl2: string = 'http://localhost:3000/facility/?';
  apiUrl3: string = 'http://localhost:3000/exposure/?';

  constructor(private http: HttpClient) {
  }
  createPerson(person: Person): Observable<any> {
    return (this.http.post(this.apiUrl1, person)
      .flatMap((response: any) => this.http.get(this.apiUrl2 + response.val1)))
  }

  getData(arg): Observable<any> {
    return (this.http.get(this.apiUrl1 + arg)
      .flatMap((response: any) => this.http.get(this.apiUrl2 + response.val1))
      .flatMap((response: any) => this.http.get(this.apiUrl3 + response.val2))
      .map((response: any) => response.val3 * response.val5)
    )
  }

}