1. 使用takeUntil取消订阅

  2. export class TestComponent {
  3.   constructor(private store: Store) { }
  4. private componentDestroyed: Subject<never> = new Subject();
  6. ngOnInit() {
  7.       this.store
  8.       .pipe(
  9.         takeUntil(this.componentDestroyed),
  10.         select(selectSiteGroupListState),
  11.       )
  12.       .subscribe(siteGroupList => {
  13.         this.siteGroupEntities = siteGroupList.entities;
  14.   }
  15. ngOnDestroy() {
  16.     this.componentDestroyed.next();
  17.     this.componentDestroyed.unsubscribe();
  18.   }
  19. }

takeUntil实现的效果是使得流进入complete状态，以达到unsubscribe状态；
另外讨论subscription的unsubscribe属性，是指observer不再订阅某个流Observable，与complete是不同的概念。以报纸订阅作为比喻：complete指报纸报社不再发行报纸，因此也无从订阅；而unsubscribe指用户不再订阅，对流（报社）本身没有任何影响。

2. subscription取消订阅

  1. var observable1 = Rx.Observable.interval(400);
  2. var observable2 = Rx.Observable.interval(300);
  4. var subscription = observable1.subscribe(x => console.log('first: ' + x));
  5. var childSubscription = observable2.subscribe(x => console.log('second: ' + x));
  7. subscription.add(childSubscription);
  9. setTimeout(() => {
  10.   // Unsubscribes BOTH subscription and childSubscription
  11.   subscription.unsubscribe();
  12. }, 1000)

这种方法本质上就是将所有订阅的subscription存入列表里然后统一取消订阅。Subscription也有一个名为
remove(otherSubscription)的方法，用来撤销已经添加到其中的其他Subscription。