Return an boolean observable reflecting the user idle state

detect-user-idle.js

function detectUserIdle(periodOfInactivity) {
  return rxjs.merge(
    rxjs.timer(periodOfInactivity),
    rxjs.merge(
      rxjs.fromEvent(document, "mousemove"),
      rxjs.fromEvent(document, "keydown"),
      rxjs.fromEvent(document, "touchstart")
    )
  ).pipe(
    rxjs.switchMap(event => !event ? rxjs.of(true) : rxjs.concat(rxjs.of(false), rxjs.throwError(() => "reset"))),
    rxjs.retry({delay: 1000}),
    rxjs.distinctUntilChanged()
  )
}