rxjs

问题 I use BehaviorSubject in my Angular app and I get observable to my Details component from DataService as shown below: DataService.ts: export class DataService { private messageTracker = new BehaviorSubject<any>(); private fileTracker = new BehaviorSubject<any>(); getMessageTracker(): Observable<any> { return this.messageTracker.asObservable(); } getFileTracker(): Observable<any> { return this.fileTracker.asObservable(); } //set methods omitted for brevity } DetailComponent : export class

问题 I'm currently struggling with multiples/forEach subscribe inside a subscribe, I'm trying to retreive a list of objects then retreive their images thanks to their ID. Currently I've done this : this.appTypeService.get().pipe( map((apps: AppTypeEntity[]) => { return apps.map((app) => new AppTypeEntity(app)); }) ).subscribe((apps: AppTypeEntity[]) => { apps.forEach((app: AppTypeEntity) => { if (app.Logo != null) { this.appTypeService.getPhoto(app.Id).subscribe((image: string) => { app.Image =

问题 I'm capturing events from an application using Rx.Observable.fromEvent in a NodeJS. These are sent to another server using request (https://www.npmjs.com/package/request). To avoid a high network load I need to buffer those events at a given timeout between sent requests. Problem Using bufferWithTime(200) will keep the node process running and I can't know when the application has finished to close the stream. Is there any way to use Rx buffers to say: When Element 1 is pushed set a timer

问题 Can anybody explain in plain English what RxJS Observavle debounce function does? I imagine it emits an event once in a while depending on the parameters, but my code below doesn't work as I expected. var x$ = Rx.Observable.fromEvent(window, 'click') .map(function(e) {return {x:e.x, y:e.y};}) .debounce(1000) .subscribe(function(el) { console.log(el); }); and the JsBin version. I expected that this code would print one click once per second, no matter how fast I am clicking. Instead it prints

问题 I'm using SystemJS to load my es2015 project into the browser. This is what I did import {Observable} from 'rxjs/Rx'; const button = document.querySelector('button'); const start$ = Observable.fromEvent(button, 'click'); In this case Observable is undefined . So I tried import Observable from 'rxjs/Observable'; In which case Observable is an object but Observable.fromEvent is undefined (it seems to be an empty object) Finally I did import Rx from 'rxjs/Rx' // Rx.Observable which did work. Any

问题 I found the rxJS docs define them as What is a Subject? An RxJS Subject is a special type of Observable that allows values to be multicasted to many Observers. While plain Observables are unicast (each subscribed Observer owns an independent execution of the Observable), Subjects are multicast. and it goes on to give examples but I'm looking for a basic ELI5 explanation. From my understanding is it helps handle and define items in a sequence. Is that correct? I think it would be most helpful

问题 On one end, I have a stream which may occasionally throw an error: this.behaviorSubject.error(error) Later on, however, I want to continue the stream: this.behaviorSubject.next(anotherValue) on the other end, I have a subscriber subscribed to behaviorSubject.asObservable() . In the subscribtion, I'm handling the value and the error: .subscribe( ( value ) => { /* ok */ }, ( error ) => { /* some error */ } ); I want the effect to be the same as a simple onSuccess and onError callback, where

问题 I have a component that gets the data from a service via http, the problem is that I don't want to hit the API backend every time I show this component. I want my service to check if the data is in memory, if it is, return an observable with the array in memory, and if not, make the http request. My component import {Component, OnInit } from 'angular2/core'; import {Router} from 'angular2/router'; import {Contact} from './contact'; import {ContactService} from './contact.service'; @Component(

问题 What would be the most idiomatic way to yield values of an Observable by a specific amount of time? For example, let's say I have an Observable created from a big Array and I want to yield a value every 2 seconds. Is a combination of interval and selectMany the best way? 回答1: For your specific example, the idea is to map each value from the array to an observable that will yield its result after a delay, then concatenate the resulting stream of observables: var delayedStream = Rx.Observable

问题 In my component template I am calling async pipe for same Observable in 2 places. Shall I subscribe to it and use returned array in my template or using async pipe for same Observable in multiple places of template has no negative effect to performence? 回答1: Every use of observable$ | async will create a new subscription(and therefor an individual stream) to the given observable$ - if this observable contains parts with heavy calculations or rest-calls, those calculations and rest-calls are