====== Observable Interval Subscription ======
The following example show how to setup a observable interval for 5 seconds. Note that observable interval will call the callback function periodically, in this case 5 seconds each, until it has been unsubscribe(). Since we unsubscribe the observable in the callback function here, it would than be a one time call. It is important to unsubscribe the observable interval once your are done with it, or it will cause memory leakage once your leave the component contains it.

{{ :ng:ng_observable.png?nolink&600 |}}

<code>
import {Component, OnInit} from '@angular/core';
import {Observable, Subscription} from "rxjs";

@Component({
  selector: 'app-root',
  template: '{{myText}}\n' +
    '<hr>\n' +
    '<button type="button" (click)="resetTimer()">Reset Timer!</button>\n',
  styleUrls: ['./app.component.css']
})

export class AppComponent implements OnInit {
  myNumbers: Observable<number>;
  mySubscription: Subscription;
  myText: string;

  ngOnInit(): void {
    this.resetTimer();
  }

  resetTimer(): void {
    if (this.mySubscription !== undefined) {
      this.mySubscription.unsubscribe();
    }
    this.myText = "Loading...";
    this.myNumbers = Observable.interval(5000);
    this.mySubscription = this.myNumbers.subscribe(
      (number: number) => {
        this.dismiss();
      }
    )
  }

  dismiss(): void {
    if (this.mySubscription !== undefined) {
      this.mySubscription.unsubscribe();
    }
    this.myText = "Done!";
  }

}
</code>