It also took me so long for such an easy solution. But I got it in the end!

cool

first time i can see "use strict" directive in kata solution

well it took me quite long to do it and while checking others solution,it looks like how easy it was but wasn't for me and now it is.

Feel free to translate it to Ruby after a decade :)

this is NOT best practice, it modifies given data

#THIEVES118

this function, although returns a string output, there is still spaces at the begining and of the string.

For some reason, I thought the toString() method was necessary at the end of this one.

Since you do not do anything with variable afterwards (besides returning it), there is no need to assign the result to a variable.

ranks cannot be changed, it's no use complaining about them ;-)

The kata is good, but I think it should be an 8 kyu not a 7.

The reduce method always returns the first argument as the total, always write 'return statement' before the first argument of the callback function,

That's so easy