What are the ways to track the change of an object in Angular 2 (analogues of $watch)?

Question

Angular

There is a common service with data in it. It is connected to different components. When you change the object of this service in one component, you need to catch these changes in another. Angular 1 has $watch, and I believe there is a $watch in Angular 2. Maybe somehow through RxJS?
Thanks in advance.

Answer 1

Found the answer. Reactive programming. The entity Rx.Subject is needed.
Below is an example on type script.

class SomeService {
  info: any = {}; // хотим отслеживать это поле
  infoSubject: Rx.Subject = new Rx.Subject();

  infoChanged(): Rx.Subject {
    return this.infoSubject;
  }

  addInfo(): void {
    this.info.blabla = '123';
    this.infoSubject.next(); // этот метод вызывает все подписанные на этот subject колбэки
  }
}

class AnotherService {
  constructor(private _someService: SomeService) {
    // подписываемся на изменения info из SomeService
    this._someService.infoChanged().subscribe({
      next: () => console.log('Object info from SomeService has changed!')
    });
  }
}