When to use Subject.prototype.asObservable() The purpose of this is to prevent leaking the “observer side” of the Subject out of an API. Basically to prevent a leaky abstraction when you don’t want people to be able to “next” into the resulting observable. Example (NOTE: This really isn’t how you should make a data source like … Read more
1) What is a “callback hell” for someone who does not know javascript and node.js ? This other question has some examples of Javascript callback hell: How to avoid long nesting of asynchronous functions in Node.js The problem in Javascript is that the only way to “freeze” a computation and have the “rest of it” … Read more
You can use (document:click) event: @Component({ host: { ‘(document:click)’: ‘onClick($event)’, }, }) class SomeComponent() { constructor(private _eref: ElementRef) { } onClick(event) { if (!this._eref.nativeElement.contains(event.target)) // or some similar check doSomething(); } } Another approach is to create custom event as a directive. Check out these posts by Ben Nadel: tracking-click-events-outside-the-current-component selectors-and-outputs-can-have-the-same-name DirectiveMetadata Host Binding
[‘a’,’b’,’c’].flatMap(function(e) { return [e, e+ ‘x’, e+ ‘y’, e+ ‘z’ ]; }); //[‘a’, ‘ax’, ‘ay’, ‘az’, ‘b’, ‘bx’, ‘by’, ‘bz’, ‘c’, ‘cx’, ‘cy’, ‘cz’] [‘a’,’b’,’c’].map(function(e) { return [e, e+ ‘x’, e+ ‘y’, e+ ‘z’ ]; }); //[Array[4], Array[4], Array[4]] You use flatMap when you have an Observable whose results are more Observables. If you have … Read more
My final solution. Works with parallel requests. UPDATE: The code updated with Angular 9 / RxJS 6, error handling and fix looping when refreshToken fails import { HttpRequest, HttpHandler, HttpInterceptor, HTTP_INTERCEPTORS } from “@angular/common/http”; import { Injector } from “@angular/core”; import { Router } from “@angular/router”; import { Subject, Observable, throwError } from “rxjs”; import … Read more
EDIT: updated code in order to reflect changes made to the way pipes work in more recent versions of RXJS. All operators (take in my example) are now wrapped into the pipe() operator. I realize that this Question was quite a while ago and you surely have a proper solution by now, but for anyone … Read more
Operators first() and take(1) aren’t the same. The first() operator takes an optional predicate function and emits an error notification when no value matched when the source completed. For example this will emit an error: import { EMPTY, range } from ‘rxjs’; import { first, take } from ‘rxjs/operators’; EMPTY.pipe( first(), ).subscribe(console.log, err => console.log(‘Error’, … Read more
Since http calls and the like are async, you get an Observable instead of a synchronous value returned. You have to subscribe to it, and in the callback in there you get the data. There is no way around that. One option would be to place your logic in the subscribe call getSomething() { return … Read more
BehaviorSubject is a type of subject, a subject is a special type of observable so you can subscribe to messages like any other observable. The unique features of BehaviorSubject are: It needs an initial value as it must always return a value on subscription even if it hasn’t received a next() Upon subscription, it returns … Read more
Please include your view and model next time (app/about/about.html and about.model). If you are returning an array, you can use the asyncPipe, which “subscribes to an Observable or Promise and returns the latest value it has emitted. When a new value is emitted, the async pipe marks the component to be checked for changes” hence … Read more