We should have JSDoc especially for the 2nd one so we can have a type annotation.  Normally the way we do it for properties like this is have a `Foo.prototype.bar = null;` to hang the docs off of & then do the init in the constructor.  But if you really hate that there's the alternative of using `@type` right here inline (though I dislike that -- mingling potentially long docs into the middle of the constructor makes its logic flow harder to read).