I have Created a Class Circle. Here
_radius is a private parameter_areaCalculate is a private methodAfter Calculate the value from private method _areaCalculate. I need this value to public method areaPrint. But it show me undefined.
const _radius = new WeakMap()
const _areaCalculate = new WeakMap()
class Circle {
constructor(r) {
_radius.set(this, r)
}
[_areaCalculate]() {
return (Math.PI * Math.pow(this.radius, 2)).toFixed(2)
}
areaPrint() {
console.log("The area of Circle is: " + _areaCalculate.get(this))
}
}
let c = new Circle(4)
c.areaPrint()If one sticks with the OP's approach of utilizing a weak map for accessing a Circle instance' "private member" through a prototypal method, then one just needs to simplify the code to a single reference map and a function which calculates a circle instance' area on the fly ...
function getComputedArea(circle) {
return (Math.PI * Math.pow(rMap.get(circle), 2)).toFixed(2);
}
const rMap = new WeakMap();
class Circle {
constructor(radius) {
rMap.set(this, radius);
}
areaPrint() {
console.log(
`A radius ${ rMap.get(this) } circle area is ${ getComputedArea(this) }`
);
}
}
let a = new Circle(4);
let b = new Circle(9);
a.areaPrint();
b.areaPrint();... or one follows VLAZ's advice and starts utilizing the private field declaration syntax for private instance fields.
Edit
From the further beneath comment-based discussion with Bergi ...
"Private methods, unlike private fields, are allocated on the prototype not on the instance, just the like their respective public counterparts" . – Bergi
... the implementation for getComputedArea changed from a local helper function to a private instance method.
class Circle {
#getComputedArea(radius) {
return (Math.PI * Math.pow(this.#radius, 2)).toFixed(2);
}
#radius;
constructor(radius) {
this.#radius = radius;
}
areaPrint() {
console.log(
`A radius ${ this.#radius } circle area is ${ this.#getComputedArea() }`
);
}
}
let a = new Circle(4);
let b = new Circle(9);
a.areaPrint();
b.areaPrint();