rxjs

问题 I am trying to set up an observable that currently receives an array of location IDs and then makes a get request for all of these at once and waits for the response for them all. Here is a sample: const fetchPhotosEpic = action$ => action$.ofType(LOCATIONS_RECEIVED) .map(action => action.payload) .mergeMap((data) => { let promiseArray = data.map(location => Observable.fromPromise(axios.get(photosUrl(location.id)))) return Observable.forkJoin( promiseArray ) }) .map(responses => responses.map

问题 I have a BehaviorSubject that I'd like to be able to filter , but maintain it's behavior-subject-like quality that new subscribers always get a value when they subscribe, even if the last value emitted was filtered out. Is there a succinct way to do that using built-in functions from rxjs? For example: const isEven = (n) => n % 2 === 0; const source = new BehaviorSubject(1); const stream = source.pipe(filter(isEven)); stream.subscribe((n) => console.log(n)); // <- I want this to print `1`

问题 I have a BehaviorSubject that I'd like to be able to filter , but maintain it's behavior-subject-like quality that new subscribers always get a value when they subscribe, even if the last value emitted was filtered out. Is there a succinct way to do that using built-in functions from rxjs? For example: const isEven = (n) => n % 2 === 0; const source = new BehaviorSubject(1); const stream = source.pipe(filter(isEven)); stream.subscribe((n) => console.log(n)); // <- I want this to print `1`

问题 I have a simple debounce on an element input event like so: Observable .fromEvent(this.elInput.nativeElement, 'input') .debounceTime(2000) .subscribe(event => this.onInput(event)); I would like to make the debounce conditional based on the value of the event when emitted, is this possible? Thanks 回答1: Yes, that's completely possible. Just make use of the debounce operator instead of debounceTime . It is passed a selector function that receives the previous operators notifaction when invoked.

问题 I have difficulties using the power of Observables i.e. RxJs 6 to correctly pipe, tap, map, mergemap or whatever my HttpClient requests. The version hell with all the different functions makes it not very easy... So what I need is to first make a REST call, then depending on the result probably do a second REST call and map the potentially two received data objects in one new data object. The function should return an Observable . So currently, I solved it with a subject that I am be able to

问题 I have difficulties using the power of Observables i.e. RxJs 6 to correctly pipe, tap, map, mergemap or whatever my HttpClient requests. The version hell with all the different functions makes it not very easy... So what I need is to first make a REST call, then depending on the result probably do a second REST call and map the potentially two received data objects in one new data object. The function should return an Observable . So currently, I solved it with a subject that I am be able to

问题 Let us say I have an Observable (hot, doesn't complete), and I subscribe to it. Ordinarily when I am finished with the Subscription I have to unsubscribe it to prevent memory leaks. let subject$ = new Subject(); const sub = subject$.subscribe(...); ... // Need to call sub.unsubscribe() when we are finished sub.unsubscribe(); sub = null; But if instead of just being finished with the Subscription I am also finished with the Observable ( Subject ) and I remove all reference to both, do I need

问题 I'm trying to create a custom async validator for my registration form where it checks if an email already exists. The backend returns 404 if the email does not exist and 200 if it does exist (can't change this old code). I have found a couple tutorials but didn't find one using the latest rxjs library. I created this Validation class: export class UniqueEmailValidator { static createValidator(httpClient: HttpClient, degree: number, wlId: number) { return (control: AbstractControl) => {

问题 I'm trying to create a custom async validator for my registration form where it checks if an email already exists. The backend returns 404 if the email does not exist and 200 if it does exist (can't change this old code). I have found a couple tutorials but didn't find one using the latest rxjs library. I created this Validation class: export class UniqueEmailValidator { static createValidator(httpClient: HttpClient, degree: number, wlId: number) { return (control: AbstractControl) => {

问题 I want to call a method after two Observables have returned values. I did some searching and it seems like forkJoin is what I want, but I can't get it to work. I know both of these Observables are returning values, as I am using the data for each individually elsewhere in the component, so clearly I'm doing something else wrong. Here is what I tried. I'm using rxjs v6.4. forkJoin( this.store.pipe(select(fromStore.getAppointmentsLoading)), this.clientStore.pipe(select(fromClientStore