Observer pattern: Implementation example

ObserverExample.ts

class SubjectExample extends AbstractSubject {
    #state = 'some interesting state';

    get state(): string {
        return this.#state;
    }

    set state(value: string) {
        this.#state = value;
        this.notify();
    }
}

const subject = new SubjectExample();

class ObserverExample implements Observer {
    constructor() {
        subject.attach(this);
    }

    public update(subjectExample: SubjectExample): void {
        console.log('Subject notified us of an update', subjectExample.state);
    }
}

const observer = new ObserverExample();

subject.state = 'new';