rxjs

问题 I have an Observable that produce the unicast value(individually for all observers). But when i am going to convert into multicast using RxJs multicast operators then it return the following error. Property 'connect' does not exist on type 'Observable' Unicast (Working Code) - let source4$ = interval(1000).pipe(take(4)); source4$.subscribe(val => { console.log(`Observer 1: ${val}`); }); setTimeout(function() { source4$.subscribe(val => { console.log(`Observer 2: ${val}`); }); }, 1000);

问题 Update The issue seems to be that the map function is not run on a "failed" request. This means that if the API I'm talking to returns a 422 Validation Failed error (or other 4xx errors) Angular will treat this as a failure and cause the Observer to run the subscribed error callback, skipping the map function in the process. Is it possible to force Angular to treat certain 4xx errors as successful requests, or force the map function to run even when an Observable returns an error? I have the

问题 I have an auth guard that needs an asynchronous response true/false when the site is visited and the user is already logged in. I'm using Firebase's onAuthStateChanged (link to docs) and it uses a callback function. How can I turn my isLoggedIn() method into something that can return Observable<boolean> ? Typscript: get isLoggedIn(): Observable<boolean> { // want something like this: return Observable.fromCallback(firebase.auth().onAuthStateChanged).map(user => !!user); // this returns () =>

问题 In RxJS, there seems to be very little difference between an Observable instance's catch method and onErrorResumeNext method, besides the fact that onErrorResumeNext concatenates the original Observable with the Observable parameters whether an error happens or not. If that's the case, isn't the naming a bit confusing? Because in case there is an error , onErrorResumeNext works exactly the same way than catch does: var testObservable = Rx.Observable.return(1).concat(Rx.Observable.throw("Error

问题 I'm trying to create an Observable from an input event. I have already tried almost everything and I can not import "fromEvent". This is my code. I am using angular 6.0.1 and RXJS 6.1.0 error TS2339: Property 'fromEvent' does not exist on type 'typeof Observable'. import { Directive, EventEmitter, Input, Output, ElementRef, ViewChild, AfterViewInit } from '@angular/core'; import { NgControl } from '@angular/forms'; import { distinctUntilChanged } from 'rxjs/internal/operators

问题 I'm trying to create an Observable from an input event. I have already tried almost everything and I can not import "fromEvent". This is my code. I am using angular 6.0.1 and RXJS 6.1.0 error TS2339: Property 'fromEvent' does not exist on type 'typeof Observable'. import { Directive, EventEmitter, Input, Output, ElementRef, ViewChild, AfterViewInit } from '@angular/core'; import { NgControl } from '@angular/forms'; import { distinctUntilChanged } from 'rxjs/internal/operators

问题 I'm new to RxJS. I know I could just .filter and .map an observable to get the change I'm looking for. But, is there any method which combines the two into one function? 回答1: Yes there is. FlatMap. Suppose you have an Observable of numbers (1, 2, 3, 4, 5, ...) and you want to filter for even numbers and map them to x*10. var tenTimesEvenNumbers = numbers.flatMap(function (x) { if (x % 2 === 0) { return Rx.Observable.just(x * 10); } else { return Rx.Observable.empty(); } }); 来源： https:/

问题 I have the following retry logic to retry an operation. It works fine for single request. For multiple on going requests, I would like to wait for existing retry logic to complete before retrying. handleError(errors: Observable<any>) { const retryCountStart: number = 1; // wait if there is any existing operation retrying // once it is complete, continue here return errors .mergeScan<any, any>( (retryCount: any, err: any) => { if (retryCount <= 5) { return Observable.of(retryCount + 1); } }

问题 I'm trying to convert an Observable into a BehaviorSubject. Like this: a$ = new Observable() b$ = BehaviorSubject.create(new BehaviorSubject(123), a$) // 🔴 I have also tried: a$ = new Observable() b$ = new BehaviorSubject(a$, 123) // 🔴 And: a$ = new Observable() b$ = a$.asBehaviorSubject(123) // 🔴 And: a$ = new Observable() b$ = a$.pipe( toBehaviorSubject(123) ) // 🔴 But none of these works. For now I have to implement like this: a$ = new Observable() b$ = new BehaviorSubject(123) a$

问题 I am new to Rxjs I am trying understand BehaviourSubject below is my code export interface State { items: Items[] } const defaultState = { items: [] }; const _store = new BehaviorSubject<State>(defaultState); @Injectable() export class Store { private _store = _store; changes = this._store.distinctUntilChanged() .do(() => console.log('changes')); setState(state: State) { this._store.next(state); } getState() : State { return this._store.value; } purge() { this._store.next(defaultState); } }