Needs description example or example test with add_-5 ( or similar negative value ). It's perfectly valid, it's within the spec, but it comes as a surprise in Submit Tests now, and surprises in Submit Tests are ++UnGood.

• if you're going to have a functional programming tag, you may want to showcase actual functional programming in your example solution.
• it is perfectly possible to sort an empty list. the result is an empty list.

I will temporarily unpublish the kata because it's missing random tests. Random tetss are a requirement for Codewars challenges. You can also use following resources for ideas how to improve your challenge:

• Codewars Authoring Guidelines
• Codewars Discord
• Authoring examples
• JavaScript Authoring Guide
• JavaScript setup docs

The best one xD