Ooh and the edge cases. Like if your last name is Null.

Many of these meanings seem to be captured in some modern solutions already:

• We plan to provide a value, but memory for this value hasn’t been allocated yet.
• The memory has been allocated, but we haven’t attempted to compute/retrieve the proper value yet
• We are in the process of computing/retrieving the value

Futures?

• There was a code-level problem computing/retrieving the value

Exception? Result monads? (Okay, yea, we try to avoid the m word, but bear with me there)

• We successfully got the value, and the value is “the abstract concept of nothingness”

An Option or Maybe monad?

• or the value is “please use the default”
• or the value is “please try again”

An enumeration of return types would seem to solve this problem. I can picture doing this in Rust.

Null was added to JavaScript because Java had it. Null is unnatural. Undefined is the canon "no value" value.

But typeof(fire_extinguisher) === "toilet_paper"

Flip the toilet roll around.

You're going to need a wet suit, an oxygen tank and scuba gear for that ..... and some air freshener or a deodorizer.

You know exactly what that picture is, and it's how I prefer to hang my toilet paper rolls because I'm in the small minority that finds it more aesthetically pleasing.

That's not true these days. You can try it yourself right in your browser's dev console.

These results are from Firefox's console.

0 == null == undefined
> false
0 == null
> false
0 == undefined
> false
null == undefined
> true
null === undefined
> false

And even in the one case where == says they are the same, you can fix that by making sure you are using === so that it doesn't do type coercion for the comparison.

Oh man, you've got me itching to get into the intricacies of JavaScript...

One fun example of the difference: when doing arithmetic operations, null is indeed converted to 0, but undefined is converted to NaN. This has to do with null being an assigned value that represents empty, whereas undefined is not actually a value but a response indicating that there was no value assigned in the first place.

NaN would be something that isn't toilet paper. So I'm gonna say a picture of a whole rotisserie chicken on the toilet paper bar.

Infinities: The toilet paper just keeps piling up until it's out of frame. It probably ends somewhere, but nowhere we can measure.

Alternately, the toilet paper it tightly wedged in the little hole and no more could be accommodated.

Subnormals: There's less than one square left, but there is still toilet paper.

-0: The glue marks on the empty tube are pointing the other way. This shouldn't matter, but is apparently enough to confuse some toilet users.

The worst thing is that the text and images are misaligned.

not undefined in mathematics, an undefined variable is just a variable that hasn't been defined (yet) and is therefore nonexistent

This is JavaScript undefined specifically where it refers to a key that isn't present.

Depends on the language afaik.

https://i.ytimg.com/vi/fcql-gXkPcg/maxresdefault.jpg