subscribeOn() v.s. observeOn()

00_subscribeOn_observeOn.js

import Rx from "rx-lite-extras";

const observable1 = Rx.Observable.create(observer => {
  console.log("[A] call onNext(1)");
  observer.onNext(1);
  console.log("[A] called onNext(1)");
  
  console.log("[B] call onNext(2)");
  observer.onNext(2);
  console.log("[B] called onNext(2)");
  
  console.log("[C] call onCompleted()");
  observer.onCompleted();
  console.log("[C] called onCompleted()");
})

const observable2 = observable1
//  .subscribeOn(Rx.Scheduler.async)    // ...(1)
//  .observeOn(Rx.Scheduler.async)      // ...(2)

console.log("[D] call subscribe()");
observable2
  .subscribe(value => {
    console.log("next: " + value);
  }, error => {
    console.log("error: " + error);
  }, () => {
    console.log("completed");
  })
console.log("[D] called subscribe()");

01_result.md

(1)subscribeOnも、(2)observeOnもない場合

const observable2 = observable1
//  .subscribeOn(Rx.Scheduler.async)    // ...(1)
//  .observeOn(Rx.Scheduler.async)      // ...(2)

[D] call subscribe()
[A] call onNext(1)
next: 1
[A] called onNext(1)
[B] call onNext(2)
next: 2
[B] called onNext(2)
[C] call onCompleted()
completed
[C] called onCompleted()
[D] called subscribe()

(1)subscribeOnがあって、(2)observeOnがない場合

const observable2 = observable1
  .subscribeOn(Rx.Scheduler.async)    // ...(1)
//  .observeOn(Rx.Scheduler.async)      // ...(2)

[D] call subscribe()
[D] called subscribe()
[A] call onNext(1)
next: 1
[A] called onNext(1)
[B] call onNext(2)
next: 2
[B] called onNext(2)
[C] call onCompleted()
completed
[C] called onCompleted()

(1)subscribeOnがなくて、(2)observeOnがある場合

const observable2 = observable1
//  .subscribeOn(Rx.Scheduler.async)    // ...(1)
  .observeOn(Rx.Scheduler.async)      // ...(2)

[D] call subscribe()
[A] call onNext(1)
[A] called onNext(1)
[B] call onNext(2)
[B] called onNext(2)
[C] call onCompleted()
[C] called onCompleted()
[D] called subscribe()
next: 1
next: 2
completed

(1)subscribeOnも、(2)observeOnもある場合

const observable2 = observable1
  .subscribeOn(Rx.Scheduler.async)    // ...(1)
  .observeOn(Rx.Scheduler.async)      // ...(2)

[D] call subscribe()
[D] called subscribe()
[A] call onNext(1)
[A] called onNext(1)
[B] call onNext(2)
[B] called onNext(2)
[C] call onCompleted()
[C] called onCompleted()
next: 1
next: 2
completed