const Observable = Rx.Observable

const Subject = Rx.Subject

​

console.clear()

console.log('[start]')

​

​

function httpRequest$(value) {

  const promise = new Promise(resolve => {

    setTimeout(() => {

      resolve(value + '!')

    }, Math.random() * 200)

  })

  return Observable.from(promise)

}

​

function log(result) {

  console.log(result)

}

​

​

httpRequest$('a').subscribe(log)

httpRequest$('ab').subscribe(log)

httpRequest$('abc').subscribe(log)

​

​

const dispatcher$ = new Subject()

const provider$ = new Subject()

​

dispatcher$

  .switchMap(value => {

    return httpRequest$(value)

  })

  .subscribe(result => {

    provider$.next(result)

  })

​

provider$

  .subscribe(log)

​

​

dispatcher$.next('A')

dispatcher$.next('AB')

dispatcher$.next('ABC')

​