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 is it possible? Maybe what I should ask is: which way I should do that?

It'll also be OK if I find a way to rewrite some response to the request instead of canceling it.

Answer 1

Inspired by @RVP answer I have found out that it's possible to cut the chain with an error in the same simple way using Observable.throw()

//... intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {     if (stopThisRequestWithError) {         return Observable.throw('Error message');     } else {         return next.handle(req);     } } 

This avoids fulfilling response promises with undefined values.

Answer 2

I think all you have to do to cut the interceptor chain is to simply return an empty Observable like so:

import { EMPTY } from 'rxjs';  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {   if (stopThisRequest) {     return EMPTY;   }    return next.handle(request); }