Isn't this a branded type / newtype / opaque type / nominal type? Edit: Ah I see, this only affects tooltips/autocomplete, doesn't actually change the behaviou

Isn't this a branded type / newtype / opaque type / nominal type? Edit: Ah I see, this only affects tooltips/autocomplete, doesn't actually change the behaviour of the type. If you want to do that you need to do something like: type UserId = number & { __type: 'UserId' };