example.js

class Rectangle {
    constructor(w, h) {
        this.w = w;
        this.h = h;
    }
}

/*
 *  Write code that adds an 'area' method to the Rectangle class' prototype
 */
Rectangle.prototype.area=function(){
    return this.w*this.h;
}

/*
 * Create a Square class that inherits from Rectangle and implement its class constructor
 */
class Square extends Rectangle{
    constructor(s)
    {
        super(s,s)
    }
    
   
}
if (JSON.stringify(Object.getOwnPropertyNames(Square.prototype)) === JSON.stringify([ 'constructor' ])) {
    const rec = new Rectangle(3, 4);
    const sqr = new Square(5);
    
    console.log(rec.area());
    console.log(sqr.area());
} else {
    console.log(-1);
    console.log(-1);
}