Day 5: Inheritance Solution
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Also visit this link: Day 4: Classes Solution
Day 5: Inheritance Solution
Objective
In this challenge, we practice implementing inheritance and use JavaScript prototypes to add a new method to an existing prototype.
Task
We provide the implementation for a Rectangle class in the editor. Perform the following tasks:
- Add an area method to Rectangle‘s prototype.
- 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 – Day 5: Inheritance
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);
}
class Square extends Rectangle {
constructor(w){
super(w, w);
}
}
/*
* Create a Square class that inherits from Rectangle and implement its class constructor
*/
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);
}