scan とか reduce とかの検証用のゴミ

gomi.js

  Rx.Observable.create((observer) => {
    setTimeout(() => {
      observer.onNext(1000);
      setTimeout(() => {
        observer.onNext(3000);
        setTimeout(() => {
          observer.onCompleted(5000);
        }, 2000);
      }, 2000);
    }, 1000);
    return observer;
  })
  .scan(((s, i) => s + i), 0) // reduce だと……
  .subscribe((i) => {
    console.log('subscribe ' + i);
  });

  Rx.Observable
    .empty()
    .scan((a, i) => console.log('empty' + i), [])
    .subscribe((i) => {
      console.log(i);
    });

    Rx.Observable
      .just([])
      .scan((a, i) => console.log('just' + i), [])
      .subscribe((i) => {
        console.log(i);
      });