SOURCE

const people = {
  year: 1,
  _time: 2005
}

Object.defineProperty(people, "time", {
  get: () => {
    return this._time;
  },
  set:(value) => {
    this._time = value;
    this.year += value - 2005;
  }
})

people.time = 2018;
console.log(people.time);
console.log(people.year)

const book = {
  _year: 2004,
  edition: 1
};
Object.defineProperty(book, "year", {
  get: function() {
    return this._year;
  },
  set: function(newValue) {
    this._year = newValue;
    this.edition += newValue -2004;
  }
})

book.year = 2015;
console.log(book.edition);