Angular2 輸入和輸出巢狀元件

一個 Button 指令，它接受 @Input() 來指定點選限制，直到按鈕被禁用。父元件可以偵聽通過 @Output 達到點選限制時將發出的事件：

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
    selector: 'limited-button',
    template: `<button (click)="onClick()" 
                       [disabled]="disabled">
                   <ng-content></ng-content>
               </button>`,
    directives: []
})

export class LimitedButton {
    @Input() clickLimit: number;
    @Output() limitReached: EventEmitter<number> = new EventEmitter();

    disabled: boolean = false;

    private clickCount: number = 0;

    onClick() {
        this.clickCount++;
        if (this.clickCount === this.clickLimit) {
            this.disabled = true;
            this.limitReached.emit(this.clickCount);
        }
    }
}

父元件使用 Button 指令並在達到單擊限制時警告訊息：

import { Component } from '@angular/core';
import { LimitedButton } from './limited-button.component';

@Component({
    selector: 'my-parent-component',
    template: `<limited-button [clickLimit]="2"
                               (limitReached)="onLimitReached($event)">
                   You can only click me twice
               </limited-button>`,
    directives: [LimitedButton]
})

export class MyParentComponent {
    onLimitReached(clickCount: number) {
        alert('Button disabled after ' + clickCount + ' clicks.');
    }
}