objectSetGet.js

let person = {
  _name: 'Lu Xun',
  _age: 137,
	set age(newAge) {
    if (typeof newAge === 'number') {
      this._age = newAge;
    } else {
      return 'Invalid input'
    }
  },
  get age() {
    console.log(this._name + ' is ' + this._age + ' years old.')
    return this._age
  }
};

person.age = 39
console.log(person.age);