JuniorTheoryCommon

What does the program print?

TypeScript

class A {
    private x = 1;
}
class B {
    #x = 1;
}
console.log(JSON.stringify(new A()), JSON.stringify(new B()));

{"x":1} {}

Expecting private to hide x from JSON.stringify: tsc erases the modifier, and in the JavaScript x is an ordinary field that JSON.stringify lists.
Expecting #x to show up like any other field: a # field is private in JavaScript itself, so neither JSON.stringify nor Object.keys sees it.

What does tsc report for new A().x and for new B().#x written outside the classes?
When is private enough, and when do you need a # field?

JuniorTheoryCommon

TypeScript

class A {
    private x = 1;
}
class B {
    #x = 1;
}
console.log(JSON.stringify(new A()), JSON.stringify(new B()));

{"x":1} {}

Expecting private to hide x from JSON.stringify: tsc erases the modifier, and in the JavaScript x is an ordinary field that JSON.stringify lists.
Expecting #x to show up like any other field: a # field is private in JavaScript itself, so neither JSON.stringify nor Object.keys sees it.

What does tsc report for new A().x and for new B().#x written outside the classes?
When is private enough, and when do you need a # field?