RxJS tips

observable_from_event_emitter.js

let everythingIsDone = Rx.Observable.fromEvent(em, ‘everythingIsDone’);
let eventSource = Rx.Observable.fromEvent(em, ‘event’).takeUntil(everythingIsDone).toArray().toPromise();

observable_overlap.js

// Could be done with simple solution using `lodash#intersection` method

Rx.Observable.merge(
  Rx.Observable.range(0, 10),
  Rx.Observable.range(11, 20),
  Rx.Observable.range(21, 25)
  )
  .scan(({intersected, set}, n) => ({intersected: set.has(n), set: set.add(n)}), 
  {intersected: false, set: new Set()}
  )
  .pluck('intersected')
  .flatMap(b => b ? Rx.Observable.throw(new Error('')) : Rx.Observable.empty())
  .subscribe(
    x => x, 
    err => console.log('There was an intersection'), 
    _ => console.log('No intersection')
  )