So if I write a class as follows
class Rectangle {
#width;
#height;
constructor() {
this.#width = 3;
this.#height = 5;
}
}
let rect = new Rectangle();
console.log(JSON.stringify(rect)); // returns {}
It will return an empty object, totally ignoring all of my private members. Adding a toJSON method works but that becomes very cumbersome. Is there any built-in way that I can easily get my private fields to show up in JSON.stringify? Or do I just have to write in every single member into a toJSON method?
Private properties are only accessible inside the class declaration itself. You'll need to write your own serialization method:
class Rectangle {
#width;
#height;
constructor() {
this.#width = 3;
this.#height = 5;
}
stringify() {
return JSON.stringify({['#width']: this.#width,['#height']: this.#height})
}
}
let rect = new Rectangle();
console.log(rect.stringify())One option to avoid having to write out all the members would be to have a single private data property on the instance, and then serialize / deserialize that property:
class Rectangle {
#data;
constructor(data) {
this.#data = data;
}
getWidth = () => this.#data.width;
toJson = () => JSON.stringify(this.#data);
}
const r = new Rectangle({ width: 1, height: 1 });
console.log(r.getWidth());
const stringified = r.toJson();
console.log(stringified);
const restructured = new Rectangle(JSON.parse(stringified));
console.log(restructured.getWidth());