AndreFeijo AndreFeijo - 5 months ago 704
AngularJS Question

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.

Answer

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.

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