/*** Helper Functions ***/

​

const showTyping = () =>

  $('.typing').text('User is typing...');

​

const showIdle = () =>

  $('.typing').text('');

​

const updateTimer = (x) =>

  $('.timer').text(x);

​

/*** Program Logic ***/

​

const inputEvents$ = Rx.Observable

  .fromEvent($('#input'), 'input');

​

const isIdle$ = inputEvents$

  .debounceTime(1000);

​

isIdle$.subscribe(showIdle);

​

const typing$ = inputEvents$

  .do(showTyping);

​

const clock$ = typing$

  .exhaustMap(() => Rx.Observable.interval(1000).takeUntil(isIdle$))

  .scan((acc) => acc + 1, 0)

  .subscribe(updateTimer);

​