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EventEmitter

用在带有 @Output 指令的组件中，以同步或异步方式发出自定义事件，并通过订阅实例来为这些事件注册处理器。

Use in components with the @Output directive to emit custom events synchronously or asynchronously, and register handlers for those events by subscribing to an instance.

      
      class EventEmitter<T> extends Subject {
  constructor(isAsync?: boolean): EventEmitter<T>
  emit(value?: T): void
  subscribe(next?: (value: T) => void, error?: (error: any) => void, complete?: () => void): Subscription
}

参见

构造函数

创建此类的实例，该实例可以同步或异步发送事件。

Creates an instance of this class that can deliver events synchronously or asynchronously.

      
      constructor(isAsync?: boolean): EventEmitter<T>
参数
isAsync boolean

When true, deliver events asynchronously.

可选. 默认值是 `false`.
返回值

EventEmitter<T>

方法

emit()

发出包含给定值的事件。

Emits an event containing a given value.

      
      emit(value?: T): void
参数
value T

要发出的值。

The value to emit.

可选. 默认值是 `undefined`.
返回值

void

subscribe()

注册此实例发出的事件的处理器。

Registers handlers for events emitted by this instance.

Registers handlers for events emitted by this instance.

      
      subscribe(observerOrNext?: any, error?: any, complete?: any): Subscription
参数
observerOrNext any

When supplied, a custom handler for emitted events, or an observer object.

可选. 默认值是 `undefined`.
error any

When supplied, a custom handler for an error notification from this emitter.

可选. 默认值是 `undefined`.
complete any

When supplied, a custom handler for a completion notification from this emitter.

可选. 默认值是 `undefined`.
返回值

Subscription

使用说明

通过添加 emit() 方法来扩展 Angular 的 RxJS Subject。

Extends RxJS Subjectfor Angular by adding the emit() method.

在以下示例中，组件定义了两个创建事件发射器的输出属性。单击标题后，发射器将发出打开或关闭事件以切换当前可见性状态。

In the following example, a component defines two output properties that create event emitters. When the title is clicked, the emitter emits an open or close event to toggle the current visibility state.

      
      @Component({
  selector: 'zippy',
  template: `
  <div class="zippy">
    <div (click)="toggle()">Toggle</div>
    <div [hidden]="!visible">
      <ng-content></ng-content>
    </div>
 </div>`})
export class Zippy {
  visible: boolean = true;
  @Output() open: EventEmitter<any> = new EventEmitter();
  @Output() close: EventEmitter<any> = new EventEmitter();

  toggle() {
    this.visible = !this.visible;
    if (this.visible) {
      this.open.emit(null);
    } else {
      this.close.emit(null);
    }
  }
}

Access the event object with the $event argument passed to the output event handler:

      
      <zippy (open)="onOpen($event)" (close)="onClose($event)"></zippy>