function Shape() {
}

Shape.prototype.getType = function() {
    return "Shape";
}

function Rectangle(a, b) {
    this.a = a;
    this.b = b;
}

Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;

const r = new Rectangle(2, 3);

console.log(r.getType());

Rectangle.prototype.getType = function() {
    return "Rectangle";
}

console.log(r.getType());