function Car(model, color){
  this.model = model;
  this.color = color;
}
Car.prototype = {
  recolor: function(newColor) {this.color = newColor},
  priceOrDefault: function(){return this.price ? this.price : 10000}
}


Object.defineProperty(Car.prototype, "all", {get: function(){ return this.model + " " + this.color} })

var car1 = new Car("BMW ", "Black");
var car2 = new Car("Lada ", "Blue")

car2.price = " 700 000 RUB"

console.log( car1.all, car2.all)
car1.recolor("silver")
console.log( car1.all, car2.all)
console.log(car1.priceOrDefault(), car2.priceOrDefault())

function User(name, age){
this.name = name;
this.age = age;
this. admin = false;
}

var u1 = new User("Vasya", 22);

User.prototype.x = 10;

u1




должно быть так: User {name: "Vasya", age: 22, admin: false, x: 10}

var F = function () {
this.a = 1;
}

var f = new F();

F.prototype.a = 44

f.a = 33

delete f.a

delete f.a

delete f.a