3 ms·
> Null means not a thing, undefined means there is not even the notion of the thing. If only "undefined" was consistently the same as lack of variable / collec
by int_19h 2y ago
> Null means not a thing, undefined means there is not even the notion of the thing.
If only "undefined" was consistently the same as lack of variable / collection entry, it would be understandable. But as things are, {x: 1, y: undefined} is not the same as {x: 1} in many ways - indeed, so much so that TS distinguishes between these two cases in its type system.