Flugelhorn reflections on JavaScript

NeighborhoodButcher

Today, for no reason at all, I was contemplating undefined in JavaScript, and what a wonderful mess it is.

> a = {}
> a.b
undefined
> 'b' in a
false

ok

> a.b = undefined
> a.b
undefined
> 'b' in a
true

ok?

> typeof undefined
"undefined"
> undefined = 1
1
> typeof undefined
"undefined"

ok...

> a.b = undefined
undefined
> typeof a.b
"undefined"
> a.b == undefined
true
> a.b = null
null
> typeof a.b
"object"
> a.b == undefined
true

...ok

> a.b = {}
{}
> typeof a.b
"object"
> a.b == undefined
false

?ok

Since undefined is a defined property of undefined type, you can define another undefined property using this defined undefined one.