if ( bmi <= 18.5 ) will return a value thus none of the following statements will be checked.

..|..

It's not necessarily obvious the 7000 is in ms. The code could alternatively be explicit/obvious about that.

oh ye you are right my bad.

impossible

This won't actuall work properly. If you have 10 for example, all 3 options will be triggered

This test should be added to the default suite
Some currently valid solutions fail on it

test.assert_equals(to_underscore("123"), "123")

done.

The point of solving the issue was making it as short as possible.
Therefore, using the arrow function and removing the brakets were neccary.

It's clever, but not best practice at all :)

Das wäre in der Tat auch eine Lösung gewesen,
aber ich wollte ja eine möglichst kurze Lösung haben. :P

Davon abgesehen, sollte man die Funktion nicht auf meine Art implementieren, und auch möglichst auch ein reverse mit anschließender for-Schleife ;D

In this case he had to remove the given brackets so this actually took longer, but very clever!

my face reading this be like: [^_-]

No need for Abs, Pow is always positive here.