Property interval does not exist in the type observable

Question

ngAfterViewInit(){
     Observable.interval(3000).timeInterval().subscribe()=>{};    
}

Trying to invoke the Observable.interval() method it is

Answer 1

import { Observable } from 'rxjs';
import { interval } from 'rxjs';
import { takeWhile } from 'rxjs/operators';

// here 20 (secs) is a reference till when it will get completed
 interval(1000).pipe(takeWhile(value => value < 20)).subscribe(
         (value: number) => {
           this.secondes = value;
         },
         (error: any) => {
           console.log('error');
         },
         () => {
           console.log('observable completed !');
         }
       );

This is a answer to how to unsubscribe.