javascript - How to do the chain sequence in rxjs

Question

I would like to to something like:

this._myService.doSomething().subscribe(result => {
  doSomething()
});
.then( () => dosthelse() )
.then( () => dosanotherthing() )

So I would like to chain .then like in promise. How would I do that in Rxjs?

this._myService.getLoginScreen().subscribe( result => {
      window.location.href = MyService.LOGIN_URL;
      /// I would like to wait for the site to load and alert something from       the url, when I do it here it alerts the old one
    });
   .then (alert(anotherService.partOfTheUrl())


getLoginScreen() {
  return this.http.get(myService.LOGIN_URL)
.flatMap(result => this.changeBrowserUrl())
.subscribe( result => //i want to do sth when the page is loaded//);
}

changeBrowserUrl(): Observable<any> {
return Observable.create( observer => {
window.location.href = myService.LOGIN_URL;
observer.next();
});
}

Answer 1

The equivalent of then for observables would be flatMap. You can see some examples of use here :

• RxJS Promise Composition (passing data)
• Why we need to use flatMap?
• RxJS sequence equvalent to promise.then()?

For your example, you could do something like :

this._myService.doSomething()
  .flatMap(function(x){return functionReturningObservableOrPromise(x)})
  .flatMap(...ad infinitum)
  .subscribe(...final processing)

Pay attention to the types of what your functions return, as to chain observables with flatMap you will need to return a promise or an observable.