class Marine {
  constructor(_damage, _armor) {
    this.damage_g = _damage;
    this.armor_g = _armor;
  }
  
  get damage() { return this.damage_g; }
  set damage(value) { this.damage_g = value; }
  
  get armor() { return this.armor_g; }
  set armor(value) { this.armor_g = value;  }
  }

  let marine = new Marine(10, 5);
  alert(marine.damage_g)
  marine.damage_g = 20;
  alert(marine.damage_g)