Generators as Observables

.js

function observable(observer) {
  for(var i = 0; i <= 10; i++) {
    observer.next(i)
  }
  observer.error()
  observer.complete()
}

const observer = {
  next(value) { console.log(`next -> ${value}`) },
  error(err) { console.log('error') },
  complete() { console.log('completed') }
}

observable(createObserver(observerGenerator()))
// observable(observer)

function createObserver(iterator) {
  return {
    next(value) { iterator.next(value) },
    error(err) { iterator.throw(err) },
    complete() { iterator.return() }
  }
}

function* observerGenerator() {
  try {
    while(true) {
      let value = yield
      console.log(`next -> ${value}`)
    }   
  } catch (err) {
    console.log('error')
  }
  
  console.log('completed')
}