class_rectangle_extend_square.js

// Use rectangle class to find the area of Square.
class Rectangle {
    constructor(w, h) {
        this.w = w;
        this.h = h;
    }
}
// Rectangle class Method to find the area.
Rectangle.prototype.area = function() {
        return(this.w*this.h);
    };
    class Square extends Rectangle {
        constructor(s) {
            super(s);
            this.h = s;
            this.w = s;
        }
    };