Comparison between native types JavaScript, Class is same than {}?

I'm writing some tests about the comparison between Class and Object in Javascript. And I have some doubt about the real objective with Class in JS.

If everything is an object(except primitives types) is correct to state that:

class Foo {
    static anyFunc () {}
}
const FooInstance = new Foo();

is equal

const FooInstance = {
    anyFunc () {}
}

?

How I can measure the performance/memory allocated/sizeof of these implementations? Can be in C++ or JS.

Thanks so much!

const FooInstance = {
    anyFunc () {}
}

FooInstance in this case is directly an instance of Object. If you look at its prototype chain, it's immediately Object. anyFunc method will be found on the instance itself.

class Foo {
  static anyFunc () {}
}
const FooInstance = new Foo();

FooInstance in this case is an instance of Foo (and Object too since all objects descend from it). If you look at its prototype chain it will have the prototype of Foo first, then the prototype of Object next. Additionally, anyFunc is not a method on the instance (nor the prototype). It will be attached on the constructor itself (i.e. Foo.anyFunc() or FooInstance.constructor.anyFunc(), but not FooInstance.anyFunc()).

In short, no. They're not equal.

Visually, the chain would look like:

// First case:
instance ---> Object.prototype
- anyFunc

// Second case:
instance -> Foo.prototype -------> Object.prototype
            - constructor (Foo)
              - anyFunc

How I can measure the performance/memory allocated/sizeof of these implementations?

It's negligble. Don't worry about it. Or worry about it only when it becomes a problem.