good shot

In that case, would it follow that the output strings could or should be declared as named variables?

Because it's good practice to name constants like this. It gives them "meaning" and makes them easier to find.

Generally, the more things you give an explicit name, the easier your code is to comprehend.

Efficiency is barely affected but yes, that's clearly over-engineered.

you're kidding...? that's a description that could be considered too long x) (but it's not).

=> not an issue in any way, closing.

The description is too long. It has to be shortened somehow.

Fixed.

It's basically the same thing as "return," and it's used in what are called "arrow functions" to cut down the lines needed to declare a function.

Where does the syntax " => " come from? What does it do?

Good point! I updated the 2nd paragraph to add this.

Nowhere in the description does it actually say to convert the input to the function into a string. That might be an oversight, but it should be added.

Random tests expect NaN as answer, but instructions specify that false is to be returned instead of NaN

Correct.