So you think this kata is out of place ? I can hear that :)

I thought that it could be fun to try and work with functionnal concepts in javascript even though it is no really a functionnal language. I had fun doing it at least.

I'm not satisfied with those constraint either. It's both too restrictive and not enough (as voile said, the problem can be bypassed using classic boolean operators).
I could disallow those too (&,| and ~) the same way, but this would further restrict indentifiers.

How can i disallow everything apart function expressions (for lambdas), function application without restricting identifiers ? I could use the AST, but i don't think that i could import external libs ... or i must read a CDN version using a http.get but that might be brittle and a bit much work for testing.

Maybe restricting identifiers to chars can be accepted ?

Yes, you can only return 5 numbers from the input array.

fixed it

Well nevermind :)

hu, that's cool ! I haven't thought that returning a pair gives you more information.
A follow-up could be nice.

fixed it

Two tests were wrong, i managed to republish with that fixed

Initially i froze the prototype of String to avoid tricks with valueOf returning a number (as Voile did).
But instead, now i just cast the result of encoded as String before comparing.
So now overloading prototypes should be ok, as well as defining method outside of encode or decode.

you are right

you want me to specify it in the kata description ?

i should never trust a copy-paste. Fixed

It should be fixed

Fixed by freezing String.prototype in preload

I added sample tests, but very basic.
I forgot to add console to the context. Now you can debug.