Как средствами JavaScript реализовать реактивность

const data = {
  _value: 0,
  get value() { return this._value },
  set value(newVal) {
    this._value = newVal;
    console.log('Value changed:', newVal);
  }
};

const reactive = (obj) => new Proxy(obj, {
  set(target, key, value) {
    target[key] = value;
    console.log(`Changed ${key} to ${value}`);
    return true;
  }
});

const state = reactive({ count: 0 });

class Observable {
  constructor() {
    this.listeners = {};
  }
  on(event, callback) {
    this.listeners[event] = callback;
  }
  trigger(event, data) {
    this.listeners[event]?.(data);
  }
}