object orientation using Object.create

by ozzymcduff

JavaScript

//Shape - superclass
function Shape() {
  this.x = 0;
  this.y = 0;
}

//superclass method
Shape.prototype.move = function(x, y) {
    console.log([this.x,this.y]);
    this.x += x;
    this.y += y;
    console.info("Shape moved.");
    console.log([this.x,this.y]);
};

// Rectangle - subclass
function Rectangle() {
  Shape.call(this); //call super constructor.
}

//subclass extends superclass
Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.shift = function(x){
    console.log('shift');
};
//Rectangle.prototype.constructor = Rectangle;

var rect = new Rectangle();

if (!(rect instanceof Rectangle)){ console.error("instance of rectangle");} //true.
if (!(rect instanceof Shape)){ console.error("instance of shape");} //true.

rect.move(2, 1); //Outputs, "Shape moved."
rect.move(1,2);
rect.shift(1);
var shape= new Shape();
console.log(shape);