TypeScript operators.catchError函數代碼示例

 /**
  * 攔截器  給請求設置 authorization 的頭
  * @param {HttpRequest<any>} req
  * @param {HttpHandler} next
  * @description
  * @returns {Observable<HttpEvent<any>>}
  */
 intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
   // 攔截請求
   let token = '43aaedb78c2ef89bb9ac1cd5f5f22ec'; // 獲取token
   let authReq = null;
   if (token) {
     authReq = req.clone({setHeaders: {Authorization: token}});
   }
   if (req.url === '/business/topology/static/export') {
     authReq = authReq.clone({setHeaders: {'Content-Type': 'form-data'}});
   }
   return next.handle(authReq || req).pipe(mergeMap((event: any) => {
       if (event instanceof HttpResponse && event.status !== 200) {
         return Observable.create(observer => observer.next(event));
       }
       return Observable.create(observer => observer.next(event)); // 獲取成功的
     }),
     catchError((err: HttpResponse<any>, caught: Observable<any>) => { // 返回異常
       if (err.status === 401) {
         this.confirmSrv.warning({
           nzTitle: '提示',
           nzContent: '登錄超時，請重新登錄！',
           nzOnOk: () => { }
         });
       }
       return Observable.create(observer => observer.next(event));
     })
   );
 }

 public getFoodRegistrations(fromDate: Moment = null, toDate: Moment = null, slot: number = null) {
   const url = this.apiService.getApiUrl('/food-registrations');
   let params = new HttpParams();
   if (fromDate != null) {
     params = params.append('from', this.dates.toLink(fromDate));
   }
   if (toDate != null) {
     params = params.append('to', this.dates.toLink(toDate));
   }
   if (slot != null) {
     params = params.append('slot', slot.toString());
   }
   return this.http.get<FoodRegistration[]>(url, {params}).pipe(
     catchError(this.handleError)
   );
 }

export function execAndWaitForOutputToMatch(cmd: string, args: string[], match: RegExp) {
  if (cmd === 'ng' && args[0] === 'serve') {
    // Accept matches up to 20 times after the initial match.
    // Useful because the Webpack watcher can rebuild a few times due to files changes that
    // happened just before the build (e.g. `git clean`).
    // This seems to be due to host file system differences, see
    // https://nodejs.org/docs/latest/api/fs.html#fs_caveats
    return concat(
      from(
        _exec({ waitForMatch: match }, cmd, args)
      ),
      defer(() => waitForAnyProcessOutputToMatch(match, 2500)).pipe(
        repeat(20),
        catchError(() => EMPTY),
      ),
    ).pipe(
      takeLast(1),
    ).toPromise();
  } else {
    return _exec({ waitForMatch: match }, cmd, args);
  }
}

 public registerFood(food: FoodRegistration) {
   const url = this.apiService.getApiUrl('/food-registrations');
   return this.http.post<{}>(url, food).pipe(
     catchError(this.handleError)
   );
 }

 public getFoodKinds() {
   const url = this.apiService.getApiUrl('/food-kinds');
   return this.http.get<FoodKind[]>(url).pipe(
     catchError(this.handleError)
   );
 }

 public login(username: string, password: string) {
   const url = this.apiService.getApiUrl('/login');
   return this.http.post(url, {username, password}).pipe(
     catchError(this.handleError)
   );
 }

 public getFoodTypes(foodKindId: number) {
   const url = this.apiService.getApiUrl(`/food-kinds/${foodKindId}/food-types`);
   return this.http.get<FoodType[]>(url).pipe(
     catchError(this.handleError)
   );
 }