rxjs - Subject 在完成后是否安全地退订其订阅者？

Question

如果我的这个类有一个在其生命周期中发出单一值的主题:

export class MyClass {
  myEmitter$: Subject<void> = new Subject();

  someMethod(){
    this.myEmitter$.next();
    this.myEmitter$.complete();
  }
}

然后在另一个类中:

this.instanceOfMyClass.myEmitter.subscribe();

鉴于主题在发射后完成，我是否应该取消订阅 instanceOfMyClass.myEmitter$？

Answer 1

当您对该主题调用complete 时，所有订阅者都将自动取消订阅。

如果您查看主题的 complete method 的来源:

complete() {
  if (this.closed) {
    throw new ObjectUnsubscribedError();
  }
  this.isStopped = true;
  const { observers } = this;
  const len = observers.length;
  const copy = observers.slice();
  for (let i = 0; i < len; i++) {
    copy[i].complete();
  }
  this.observers.length = 0;
}

您会看到主题对其每个观察者调用 complete。和 Observable Contract指出:

When an Observable issues an [error] or [complete] notification to its observers, this ends the subscription. Observers do not need to issue an [unsubscribe] notification to end subscriptions that are ended by the Observable in this way.