How to cancel current request in interceptor - Angular 4

Question

As you know it\'s possible to use Interceptors in new versions of Angular 4.

In mine, I want to cancel a request in interceptor in some conditions. So i

Answer 1

let sub = this.http.get(url, {headers: reqHeaders})
            .subscribe(
                (res) => {
                    res = res.json();
                }
            );

sub.unsubscribe();