Discussion on Day 5: Inheritance Challenge

8 years ago+ 1 comment

what's wrong with my code??

/*
 *  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){
            this.s = s;
        }
        area() {
            return (this.s*this.s);
        }
    }

HackerRank AdminChallenge Author 8 years ago+ 1 comment

You should call the constructor of the parent class from the child class, i.e., the Square class constructor should call super(s, s).

You can check the editorial.

7 years ago+ 1 comment

I noticed utilizing super() and super(s) can pass the test case, too. Why is that? Thank you.

7 years ago+ 0 comments

super() initializes its parent constructor. In this case it calls constructor of Rectangle. So using super(s,s) will initialize w and h.

Rectangle.prototype.area = function() {
    return(this.w*this.h);
};

class Square extends Rectangle {
    constructor(s) {
        super(s,s);
    }
};

However if you do not provide proper argument to super then you have to manually assign the value of w and h. Like:

class Square extends Rectangle {
    constructor(s) {
        super()
        this.w = s;
        this.h = s;
    }
};

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