Programming Concepts — Observer Pattern

The Observer pattern allows objects to subscribe to changes in another object, enabling reactive programming.

class Subject {
  constructor() {
    this.observers = [];
  }
  subscribe(observer) {
    this.observers.push(observer);
  }
  notify(data) {
    this.observers.forEach(obs => obs(data));
  }
}

const subject = new Subject();
subject.subscribe(data => console.log('Observer 1:', data));
subject.notify('Update received');