小编J. *_*lds的帖子

我不明白为什么子组件的更改检测在这种情况下运行：

import { Component, ChangeDetectionStrategy } from '@angular/core'

@Component({
  selector: 'app-root',
  template: `
    <cmp [ticks]="ticks" (update)="onUpdate($event)"></cmp>
  `,
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class AppComponent {

  ticks = 0;

  onUpdate(event) {
    console.log(this.ticks);
  }
}


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

@Component({
  selector: 'cmp',
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `<p>Number of ticks: {{ticks}}</p>
`
})
export class CmpComponent implements OnInit, OnChanges {
  @Input('ticks') ticks: number;
  @Output() update: EventEmitter<number> = new EventEmitter();

  ngOnInit() {
    setInterval(() => {
      this.ticks++;
      this.update.emit(this.ticks);
    }, …