function Car() {}
car1 = new Car();
car2 = new Car();
console.log(car1.color); // undefined
Car.prototype.color = "original color";
console.log(car1.color); // original color
car1.color = 'black';
console.log(car1.color); // black
console.log(car1.__proto__.color) //original color
console.log(car2.__proto__.color) //original color
console.log(car1.color) // black
console.log(car2.color) // original color