just a syntax error, put 'let' before i in the for loop.

After seeing this solution, i learned that, in contrast to BST in other languages, BST(Set) in javascript can hold its insertion order.
This solution is clean and stable.

unpowerful

I don't like this solution because you are mutating the function argument.

Great! solution!

Same solution as mine, but you have a great use of naming and aliases to make it more readable.

just genius

same with mine) good though

My solution was almost same, without the destructuring. That's nice!

This is great! I like it

That's a more readable solutiont than with reg exp

Simple and Сlearly

As for me the best sol., and liberates you from learning REG EXP