I think `in` and `instanceof` could both benefit from having negated
versions.
Assuming the developer is using `in` correctly, hasOwnProperty concerns are
irrelevant. Either way they would attempt to use !(a in b), not
!hasOwnProperty.
Same reason we don't use...
!(a == b) // a != b
!(a === b) // a !== b
!(a > b) // a <= b
(!(a > b) && !(a == b)) // a < b
On Thursday, June 28, 2018, Tobias Buschor <tobias.busc...@shwups.ch> wrote:
> I dont like to write:
> if ( !('x' in obj) && !('y' in obj) ) {
> doit()
> }
>
> I was even tempted to write it that way:
> if ('x' in obj || 'y' in obj) { } else {
> doit()
> }
>
> What about a !in operator to write it like this?
> if ('x' !in obj && 'y' !in obj) {
> doit()
> }
>
>
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