Day 5: Inheritance:- 10 Days of JavaScript HackerRank Solution

Problem:-

Objective

In this challenge, we practice implementing inheritance and use JavaScript prototypes to add a new method to an existing prototype. Check out the attached Classes tutorial to refresh what we've learned about these topics.

Task

We provide the implementation for a Rectangle class in the editor. Perform the following tasks:

1. Add an area method to Rectangle's prototype.
2. Create a Square class that satisfies the following:
   • It is a subclass of Rectangle.
   • It contains a constructor and no other methods.
   • It can use the Rectangle class' area method to print the area of a Square object.

Locked code in the editor tests the class and method implementations and prints the area values to STDOUT.

Solution:-

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);

this.h = s;

this.w = s;

}

};

if (JSON.stringify(Object.getOwnPropertyNames(Square.prototype)) === JSON.stringify([ 'constructor' ])) {

const rec = new Rectangle(3, 4);

const sqr = new Square(3);

console.log(rec.area());

console.log(sqr.area());

} else {

console.log(-1);

console.log(-1);

}