Rx.Observable.merge(

  Rx.Observable.timer(2000).mapTo(2000),

  Rx.Observable.timer(1000).mapTo(1000),

  Rx.Observable.timer(3000).mapTo(3000)

).subscribe(

  x => console.log(`next: ${x}`),

  error => console.error(`error: ${error}`),

  () => console.log('complete')

);

// => "next: 1000"

// => "next: 2000"

// => "next: 3000"

// => "complete"