An example of retryWhen while making sure that the last error is the one that gets thrown. The answer is a bit less clean but no less powerful, just use one of the flattening map operators (concatMap, mergeMap, switchMap) to check which index you are at.
loadSomething(): Observable<SomeInterface> {
const retryPipeline =
// Still using retryWhen to handle errors
retryWhen(errors => errors.pipe(
// Use concat map to keep the errors in order and make sure they
// aren't executed in parallel
concatMap((e, i) =>
// Executes a conditional Observable depending on the result
// of the first argument
// here the role of iif is not to execute one path over the other,
// but to subscribe to one Observable or the other
iif(
() => i > 10,
// If the condition is true we throw the error (the last error)
throwError(e),
// Otherwise we pipe this back into our stream and delay the retry
of(e).pipe(delay(500))
)
)
return this.http.get(this.someEndpoint, commonHttpHeaders())
// With the new syntax you can now share this pipeline between uses
.pipe(retryPipeline)
}