function Person(age, name) {
    this.name = name;
    this.age  = age;
  };
  
  Object.defineProperty(Person.prototype, "age", {
    get: function() {
      return this._age;
    },
  
    // Added a few things to demonstrate additional logic on the setter
    set: function(num) {
      num = parseInt(num, 10);
      if(num > 0) {
        this._age = num;
      }
    }
  });

console.log(Person.prototype.hasOwnProperty('age'))
console.log(Person.hasOwnProperty('age'))

if(!(Person.prototype.hasOwnProperty('age'))){
  Object.defineProperty(Person.prototype, "age", {
    get: function() {
      return this._age;
    },
  
    // Added a few things to demonstrate additional logic on the setter
    set: function(num) {
      num = parseInt(num, 10);
      if(num > 0) {
        this._age = num;
      }
    }
  });
}
  
  a= new Person(1,2)
  a.name=10
  console.log(a.age)