Angular 2 polling with RxJS

I'm trying to poll a RESTful endpoint to refresh my live chat messages. I know the best approach for a live chat would be Websockets, I'm just trying to understand how RxJS works with Angular 2.

I want to check for new messages every second. I have the following code:

return Rx.Observable
   .interval(1000)
   .flatMapLatest(() => this.http.get(`${AppSettings.API_ENDPOINT}/messages`))
   .map(response => response.json())
   .map((messages: Object[]) => {
      return messages.map(message => this.parseData(message));
   });

However my Typescript transpiler is returning this error:

Property 'flatMapLatest' does not exist on type 'Observable<number>'

I'm using RxJS 5.0.0-beta.0

If I use merge instead of flatMapLatest it doesn't call the API at all.

Solution

You need to use switchMap(), there's no flatMapLatest() in RxJS 5.

See Migrating from RxJS 4 to 5... Although docs aren't very clear about switchMap()...

Returns a new Observable by applying a function that you supply to each item emitted by the source Observable that returns an Observable, and then emitting the items emitted by the most recently emitted of these Observables.