In Angular 2 you can subscribe (Rx event) to a Router instance. So you can do things like class MyClass { constructor(private router: Router) { router.subscribe((val) => /*whatever*/) } } Edit (since rc.1) class MyClass { constructor(private router: Router) { router.changes.subscribe((val) => /*whatever*/) } } Edit 2 (since 2.0.0) see also : Router.events doc class … Read more
I think that you need to import this: import ‘rxjs/add/operator/map’ Or more generally this if you want to have more methods for observables. WARNING: This will import all 50+ operators and add them to your application, thus affecting your bundle size and load times. import ‘rxjs/Rx’; See this issue for more details.
So the answer is no, you don’t. Ng2 will clean it up itself. The Http service source, from Angular’s Http XHR backend source: Notice how it runs the complete() after getting the result. This means it actually unsubscribes on completion. So you don’t need to do it yourself. Here is a test to validate: fetchFilms() … Read more
A BehaviorSubject holds one value. When it is subscribed it emits the value immediately. A Subject doesn’t hold a value. Subject example (with RxJS 5 API): const subject = new Rx.Subject(); subject.next(1); subject.subscribe(x => console.log(x)); Console output will be empty BehaviorSubject example: const subject = new Rx.BehaviorSubject(0); subject.next(1); subject.subscribe(x => console.log(x)); Console output: 1 In … Read more
Angular v2 doesn’t support more than one structural directive on the same element. As a workaround use the <ng-container> element that allows you to use separate elements for each structural directive, but it is not stamped to the DOM. <ng-container *ngIf=”show”> <div *ngFor=”let thing of stuff”> {{log(thing)}} <span>{{thing.name}}</span> </div> </ng-container> <ng-template> (<template> before Angular v4) … Read more
Basically, you write a pipe which you can then use in the *ngFor directive. In your component: filterargs = {title: ‘hello’}; items = [{title: ‘hello world’}, {title: ‘hello kitty’}, {title: ‘foo bar’}]; In your template, you can pass string, number or object to your pipe to use to filter on: <li *ngFor=”let item of items … Read more
TL;DR: No, don’t subscribe manually to them, don’t use them in services. Use them as is shown in the documentation only to emit events in components. Don’t defeat angular’s abstraction. Answer: No, you should not subscribe manually to it. EventEmitter is an angular2 abstraction and its only purpose is to emit events in components. Quoting … Read more
What is the difference between Promises and Observables?
As in latest release of Angular (v6.1.0) , Angular Team has added new built in pipe for the same named as keyvalue pipe to help you iterate through objects, maps, and arrays, in the common module of angular package. For example – <div *ngFor=”let item of testObject | keyvalue”> Key: <b>{{item.key}}</b> and Value: <b>{{item.value}}</b> </div> … Read more
Update 2016-06-27: instead of using Observables, use either a BehaviorSubject, as recommended by @Abdulrahman in a comment, or a ReplaySubject, as recommended by @Jason Goemaat in a comment A Subject is both an Observable (so we can subscribe() to it) and an Observer (so we can call next() on it to emit a new value). … Read more