Angular 2 ngOnChanges仅用于特定绑定

Question

是否有可能只检测angular2中特定绑定属性的更改？

 export class Test{
     @Input() a;
     @Input() b;
     constructor() {
         }

     ngOnChanges(){
         //I want that this only called when a changed
         console.log(this.a);
     }
}

Answer 1

正如埃里克所说,这个ngOnChanges方法将在你@Input的每次更新时被调用.

如果您只想检测@Input"a" 的更新,可以使用setter:

export class SubComponent {
  @Input()
  set a(a:string) {
    this._a = a;
    console.log('a updated');
  }

  @Input()
  b:any;

  (...)
}

请参阅此plunkr:https://plnkr.co/edit/UKyRiq ？ p = preview .