RxJs Observables nested subscriptions?

Question

Whats the way to simplify something like the following code example? I can\'t find the right operator.. could anyone give a short example?

this.returnsObserv         


        

Answer 1

The switchMap operator can also be useful. Some examples which describe the usefulness of switchMap compared to nested subscriptions can be found here:

1. situation with nested subscriptions

This codepen gives a demo: https://codepen.io/anon/pen/zdXBvP?editors=1111

Rx.Observable
  .interval(5000)
  .subscribe((val) => {
    console.log("outer:", val);
    Rx.Observable
      .interval(1000)
      .subscribe((ival) => {
        console.log("inner:", val, ival); 
      });
  });

2. situation with switchMap

This codepen gives a demo: https://codepen.io/anon/pen/xLeOZW?editors=1111

Rx.Observable
  .interval(5000)
  .switchMap((val) => {
    console.log("outer:", val);
    return Rx.Observable.interval(1000).map((ival) => [val, ival]);
  })
  .subscribe((val) => {
    console.log("inner:", val[0], val[1]);
  });