Day 5: Inheritance

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

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/*
 *  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);
    }
}