I don't use - may the mods forgive me for using this dirty word - JavaScript, but I have seen other people make this comment before, and it seems to be because the_function_you_are_trying_to_use is not implemented in the Node.js version of this kata (I have no idea what Node.js is - just repeating what I've seen in other comments).

I hope that helps you google a bit for alternatives, until a Codewars user with JS experience sees your question and can help out more than me.