javascript - Return an empty Observable

Question

The function more() is supposed to return an Observable from a get request

export class Collection {
  public more = (): Observable<Response> => {
    if (this.hasMore()) {
      return this.fetch();
    } else {
      // return empty observable
    }
  };

  private fetch = (): Observable<Response> => {
    return this.http.get("some-url").map((res) => {
      return res.json();
    });
  };
}

In this case I can only do a request if hasMore() is true, else I get an error on subscribe() function subscribe is not defined, how can I return an empty Observable?

this.collection.more().subscribe(
  (res) => {
    console.log(res);
  }, (err) => {
    console.log(err);
  }
);

Update

In RXJS 6

import { EMPTY } from 'rxjs'
return EMPTY; 

Answer 1

For typescript you can specify generic param of your empty observable like this:

import 'rxjs/add/observable/empty' 

Observable.empty<Response>();