Challenge 3 — Solution

Task: Define a class Circle with a constructor taking radius, and a
getter area returning the circle's area (π × radius², using 3.14159
for π) and a getter circumference returning 2 × π × radius. Create
an instance and log both computed properties.

class Circle {
    constructor(radius) {
        this.radius = radius;
    }

    get area() {
        return 3.14159 * this.radius ** 2;
    }

    get circumference() {
        return 2 * 3.14159 * this.radius;
    }
}

const circle = new Circle(5);

console.log(circle.area);
console.log(circle.circumference);


Expected output:

78.53975
31.4159


Notes:
- circle.area and circle.circumference are accessed WITHOUT
  parentheses, even though they're really methods underneath —
  that's the entire point of a getter, making a computed value read
  like a plain property.
- this.radius ** 2 squares the radius, reusing the exponentiation
  operator from Chapter 2's makePowerOf example.
- Neither value is stored separately — both are recalculated fresh
  every time they're read, so they could never drift out of sync
  with radius even if radius changed after the instance was created.