isArray has unnecessary code

[kirilloid]

Why do we need that extra !!?

[false, null, undefined, NaN, 0, ''].filter(Array.isArray)

is empty, no falsy value is considered as an array

Maybe, I can create a PR with several such small changes instead of writing about every separately?

[Chalarangelo]

To convert to a boolean value. This was mentioned before and was actually PRed to fix the issue of the return value not always being boolean.

[kirilloid]

But you don't need !!val && (or val &&) part at all! Just use Array.isArray

[Chalarangelo]

You need it to check if the array is empty or something like that.

[kirilloid]

No, it is not needed.
There are only six falsy (which result in false when converted to Boolean, e.g. with !!) values in JavaScript, all enumerated in my first comment.

[dfdeagle47]

To add more context, the PR in question is #130 which fixes #111, i.e.

const isArray = val => val && Array.isArray(val);
// isArray(null) -> null (not false)

which was changed to

const isArray = val => !!val && Array.isArray(val);
// isArray(null) -> false

However, as @kirilloid just said, the first part of the expression is unneeded, it should read

const isArray = val => Array.isArray(val);

Unless I'm unaware of some implementation difference between different engines, Array.isArray() always returns a boolean value, and correctly works with the different falsy values.

[Chalarangelo]

@dfdeagle47 there's actually some controversy regarding this particular snippet, as there is a slight chance we might remove it entirely iff we only need to check Array.isArray(), so until we figure that out it might be irrelevant making changes in case we delete it in the end.

[dfdeagle47]

@Chalarangelo : ok makes sense now, I didn't know that part of the discussion.

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