为什么ReplaySubject返回所有值？

Question

我有服务：

private publishSubscribeSubject_: ReplaySubject<any> = new ReplaySubject();
private emiter_: Observable<any>;

public publish(channel: EventsChannels, event: any) {
   this.publishSubscribeSubject_.next({ channel: channel, event: event });
}

public subscribe(channel: EventsChannels[] | EventsChannels , handler: (value: any) => void) {
   return this.emiter_
      .filter(emission => emission.channel === channel)
      .map(emission => emission.event)
      .subscribe(handler);
}

在组件中使用：

ngOnInit() {
    this.objectDetailsSubscription = this.eventService.subscribe(
      EventsChannels.OBJECT_DETAILS,
      semantic => {
        console.log(semantic);
      }
    );
  }

为什么每次激活组件时，我都会从ngOnInit() {}中看到ReplaySubject中的所有最后一个值？

<app-object-details *ngIf="menuItemType === menuItemTypes.ObjectDetails"></app-object-details>

Answer 1

除非您通过执行以下操作指定应有多少个“重播”：

new ReplaySubject(2) // Will replay last 2 values

您将始终获得所有值。

查看此链接以了解更多信息：

https://www.learnrxjs.io/learn-rxjs/subjects/replaysubject