Thanks for that, you right! I've updated the Kata. Back then I possibly fooled myself, because NaN and Infinity is autoboxed into a Number without the need of () or space after 1. <- dot.

"add" and its results must return function. Otherwise such results couldnt be called, so no chaining wouldn't work.
The kata's description doesnt show important nuance - the result must play as function in context of comparison or arithmetic operations, e.g.

add(1)(2) == 3

NodeJS command line interface output result of last operation as is - without any conversion, so you see function. It's because only a primitive value can evaluate to primitive without conversions (explicit or implicit). And browser console typically performs conversion to a string when it prints result of last command.

goto(2, 12)
=> 10

Nah, I won't use your elevator :)

Huh, the description says

Write a function that takes a string and turns all words of length 3 or greater into an abbreviation

But when I change a word of length 3, test case says:

Test Failed: Input: "is balloon is doggy mat" - Expected: is b5n is d3y mat, instead got: is b5n is d3y m1t

yup, that looked strange. I'll close it then :)

Well, looks like tests are broken. Actually only 3 asserts are executed, and all that following randomising code checks nothing. Now there are at least some solutions that are incorrect (including my first solution)

This one is better. This kata had finally teached me how direct/indirect eval works. And some other things too. Thank you, @bloos! ^)

Geeeee, I thought it was impossible! ^_^ It took me >10 hours, several days to try so frikkin much ways. Unfortunately, it's still the same trick that @mrkishi has already used. Ahh, I wished to gain some uniqueness! Nooot this time -_- Anyway, the kata is superinteresting.

Yo, guys xD PASSED ^_^

answered already for another solution

what kata is it?