Angular HttpClient request with retry and delay is sending an extra request then canceling it

Question

Am trying to use the Angulars HttpClient service to make a request with a number of tries and a delay in between. The code works, but i noticed in the devTools network tap that in the end an extra request is sent and canceled. What am I doing wrong here is the code:

return this.http.post<LoginSuccessPayload>('/api/auth/signin', payload).pipe(
  retryWhen(errors => {
    return errors.pipe(
      mergeMap((er: any) => {
        if (er.status === 504 || er.status === 503) {
          return of(er.status).pipe(delay(1000));
        }
        return _throw({message: er.error.message || 'Notification.Core.loginError'});
      }),
      take(3),
      concat(_throw({message: 'Notification.Core.networkError'}))
    );
  })
);

Here is an Image of Firefox and Chrome network tab, there should be three request but its making four and canceling the last one

Answer 1

Here is how I solved it. now three tries with a second delay per request and no extra canceled request

 return this.http.post<LoginSuccessPayload>('/api/auth/signin', payload).pipe(
  retryWhen(errors => errors.pipe(
    switchMap((error) => {
      if (error.status === 504 || error.status === 503) {
        return of(error.status);
      }
      return _throw({message: error.error.message || 'Notification.Core.loginError'});
    }),
    scan(acc => acc + 1, 0),
    takeWhile(acc => acc < 3),
    delay(1000),
    concat(_throw({message: 'Notification.Core.networkError'}))
  ))
);

Answer 2

Below is my HttpInterceptorService Code. Code is working fine as excepted. I would like to retry based on count. Let say my initial retryWaitMilliSeconds = 300 and retryCount = 3

First time I want to retry with 300 * 1

Second time I want to retry with 300 * 2

Third time I want to retry with 300 * 3

private retryCount = 3;
private retryWaitMilliSeconds = 500;

intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

        let ok: string;
        const started = Date.now();

        // Handle request
        request =    request.clone({
            setHeaders: {
                "Authorization": "Bearer  XXXXXXXXXXXXXXXXXXX"
            }
        });

        return next.handle(request).pipe(
            tap(event => ok = event instanceof HttpResponse ? 'succeeded' : ''),
            retryWhen(error => error.pipe(concatMap((error, count) => {
                ok = 'failed'
                if (count <= this.retryCount && error.status === 500) {
                    return of(error);
                }
                return throwError(error);
            }), delay(this.retryWaitMilliSeconds),
                tap(err => console.log("Retrying...")))
            ), finalize(() => {
                
            }))
    }