Angular & Signals (283 Qs)•Part 1: Architecture, Components, Directives & Lifecycle (1 - 35)
What is the purpose of async pipe?
The AsyncPipe subscribes to an observable or promise and returns the latest value it has emitted. When a new value is emitted, the pipe marks the component to be checked for changes.
Let's take a time observable which continuously updates the view for every 2 seconds with the current time.
typescript
@Component({
selector: 'async-observable-pipe',
template: `<div><code>observable|async</code>:
Time: {{ time | async }}</div>`
})
export class AsyncObservablePipeComponent {
time: Observable<string>;
constructor() {
this.time = new Observable((observer) => {
setInterval(() => {
observer.next(new Date().toString());
}, 2000);
});
}
}