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.