Truthfulness of empty arrays in Javascript… that’s not cool!


An empty array when cast to Boolean evaluates true, indicating that it is truthy.

Boolean([])
true

An empty array compared to true evaluates false, indicating that it is not truthy.

[] == true
false
[] == false
true

And yet the Boolean opposite of an empty array still evaluates false, implying that the empty array is truthy.  What’s an interpreter to do?

![]
false
!![]
true

Just some more contradictory anecdotal evidence to help drive you mad.

Boolean([]) == []
false
Boolean([]) == ![]
false
Boolean([]) == !![]
true
!Boolean([]) == []
true

Conclusion?  I’ll just bit my tongue this time.

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About andyortlieb

I've been a tinkerer and a lazy ideologist since I gained my first personal computer in 1989. I have an aversion to formal education and I prefer to learn things by experimentation. That is not a brag, it has not been a particularly helpful set of traits. My primary goals are to increase my safety, pleasure and usefulness as I work to build and modify technologies that will bring those same attributes to the masses irrespective of government. This is the documentation of my attempt at that journey.
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