All deprecated items are marked as @deprecated in JSDoc.
But there're some level of deprecations.
They are marked as @deprecated but there are not in the next "As Not Recommended" section.
We don't have any concrete plan to remove followings but do not recommend to use them in almost cases.
Option<T> ({ ok: true; val: T } | { ok: false; }) (deprecated)
Basically, we don't recommend to use this type. Use Nullable, Undefinable<T>, or Maybe<T> to express an absence of a value instead. In JavaScript, they would cover almost usecases. Probably, you might not have to use this type.
This can express that there is some values or none as a plain object. This does not have any property method on its prototype. But this allows no including unused methods of them.