Thank you for making this Kata.
I really enjoyed it.

I completed this Kata in JavaScript, but I'm curious about why white spaces (' ') are accpeted between words, but non-breaking spaces ('\xa0') are not accepted.

As far as I know, non breaking spaces do not collapse when rendered in HTML, while normal spaces might be collapsed.

Thanks.

Thanks again :)
My first algorithm was too slow, by selecting Node v0.10 in the dropdown menu and submitting the solution I saw it time out after 130 tests.
The error message I reported in my first post appeared with the default settings, Node v6 selected (and the message was quite confusing, because it seemed something server side).

My second algorithm had a "isPrime" function, but was slow because I was creating an array with all primes up to "n".

After some more attempts I managed to get it right.

Nice challenge :)