interval and take

  Rx.Observable.interval(1000).take(5).subscribe(
    element => console.info(element),
    error => console.info(error),
    () => console.info('I am done!')
  );

The observable above will produce a value every 1000ms, only the first 5 values will be emitted due to the use of take, otherwise the sequence will emit values indefinitely. There are many more operators available within the API, such as range, timer etc.