Sbject是一种特殊的Observable,区别在于Subject可以将值传递给多个观察者,而Observable一般情况下是一对一的。Subject的作用是当我们需要告诉其他组件当前组件的值发生了变化时,可以通过Subject主动向外发送一个值,而需要感知这个组件值变化的组件就可以订阅这个值,通过这种方式感知组件发生变化,或在不同组件之间传
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我遇到了同样的问题,但在这个线程中从 @jonrsharpe 得到了答案:Unit test Angular 2 service subject。 您需要在测试的早期、调用之前声明您的主题订阅next()。如果你像这样重新排序,它应该可以工作: it('should send the text to detect the change', async((done) => { titlebarComponent.searchChange.subscr...
问Angular observables -如果没有订阅，我需要取消订阅吗？EN简而言之，是的，您仍然在avoid subscription...
Likewise, it is important to understand the difference between Observable, EventEmitter, and Subject and where to use it. It always gets confusing to choose between Eventemitter and Subject for transferring data from one component to another component. What is observable? Angular uses observables as...
可以使用subject.asObservable() Subject和BehaviorSubject创建可观察对象。 唯一的区别是您无法使用next()方法将值发送给可观察对象。 在Angular 服务中,我将对BehaviorSubject ,因为有角度的服务通常在组件和行为主体确保使用该服务的组件接收到最后更新的数据之前就进行初始化,即使自组件订阅该数据以来没有新的更新也是如此...
我有一个 Angular 2 服务: import {Storage} from './storage'; import {Injectable} from 'angular2/core'; import {Subject} from 'rxjs/Subject'; @Injectable() export class SessionStorage extends Storage { private _isLoggedInSource = new Subject<boolean>(); isLoggedIn = this._isLoggedInSource...
Another thing I’ve seen is storing the subscriptions in a Subscription array and then unsubscribing using “forEach” in the destroy. let subs: Subscription[] = []; ngOnInit() { this.subs.push(this.service.Subject1.subscribe(() => {})); ...
@DaemonExMachina to me it is a question of the public API of EventEmitter because it feels like that the Subject was exposed by accident and people use it, even tho Angular is not committed to supporting it. If EventEmitter would not have a public API of Subject (as in, not extending ...
在观察者模式中,一个名为“可观察对象(Observable)”或“Subject”的对象维护着一个名为“观察者(Observers)”的订阅者集合。当Subjects的状态发生变化时,它会通知所有的观察者。 在JavaScript中,最简单的例子是事件发射器(event emitters)和事件处理程序(event handlers)。