I understand that, but it is always a good practice to remember applying the second argument according to various cases

if you don't pass 0 insted of it will be first elemment of an array, that means you don't need 0

this called sparring, spar to get better

Wtf? Iv started js week ago, but im just simple dont understand which language thats writted by xd

I love this approach, awesome!

Thanks for informing me, That's certainly not an accurate implementation for passing all possible tests, I applied a different answer considering this problem.

'A tree is hidden if it is shorter than or the same height as a ( any ) tree in front of it, as seen in a particular direction.'

What if there is a list with the following sequence [2, 1, 5, 3, 4, 4, 9, 6, 4, 2, 5, 1, 2]? According to your function, there are 6 trees visible on the left side and 5 on the right side. In this case, your function returns "left". But actually 3 trees are visible on the left side and 4 on the right side. The function should return "right"

Due to the imperfection of the tests, this solution passes, but it should not. Correct me if I'm wrong.

clever solution !

same line of thoughts...! completed the code in very list line ...! but, you add 'map' to form array . super bro.!

Can extract the duplicative + '...' from inside the parentheses and place at the end of the falsy execution.

the array should not be altered..