Calling it a bad method is not correct.
It is a naive method, and not intended to be fast.

It is a useful attempt, because it works - and for CodeWars, we get to see the more advanced answers, and try to understand how they work.
These are often written with functions and methods that newer coders do not know exist, or that are difficult to parse.

And if anyone ever accidentally passes a second argument to solve, it'll break ( unless it's exactly the right value for the bug because of == instead of === ).

also can't copy-paste from over there and have to actually type lol

But then you'd have to type all those quotes and commas!!

It is since Java 8 (didn't know about it either)

Finding the minimum and maximum element in an array has O(n) time complexity, whereas sorting the input takes O(n log(n)). So yes, it will be noticeably faster for larger arrays.

This is done to rule out e.g. leading 0's.
It's first turned into a number, then into a string and finally compared to the original.
String(Number("01")) is "1", which is not equal to "01".

bad method

Basically, he took advantage of the Javascript runtime used to process and verify the solution, which is NodeJS. And NodeJS has this built-in IP Checker function. So yeah, it's actually cheating xD

Exactly

You dont have to reverse an array when you can
just traverse it from the end to start.
Thus you dont have to even transfrom your array
into an object of List.

(sqrt2 - 1) ** 2 = 3 - 2sqrt2