Is it necessary to unsubscribe from observables created by Http methods?

Question

Do you need to unsubscribe from Angular 2 http calls to prevent memory leak?

 fetchFilm(index) {
        var sub = this._http.get(`http://example.com`)
              


        

Answer 1

Calling the unsubscribe method is rather to cancel an in-progress HTTP request since this method calls the abort one on the underlying XHR object and remove listeners on the load and error events:

// From the XHRConnection class
return () => {
  _xhr.removeEventListener('load', onLoad);
  _xhr.removeEventListener('error', onError);
  _xhr.abort();
};

That said, unsubscribe removes listeners... So it could be a good idea but I don't think that it's necessary for a single request ;-)

Hope it helps you, Thierry