Tail recursion is its own reward

Taking advantage of the fact that Array.prototype.push returns the final array's length.

not aligning those map functions? smh

  ...bananas(s.slice(1),banana.slice(1)).map( v => s[0] + v )
, ...bananas(s.slice(1),banana         ).map( v => "-"  + v )
) :
     bananas(s.slice(1),banana         ).map( v => '-'  + v ) ;

https://www.youtube.com/watch?v=EVVWqIA9FlI

Squint and see Haskell.

Your less idiomatic solutions using add1 and sub1 intrigue me.
I wonder if this style disregards efficiency though.

This solution fails for ambiguous sampling.

signal = "11111111000000"
discrete = map length . group $ signal

minimum discrete == 6
foldl' gcd 0 discrete == 2

the minimum might be a different value than the greatest common denominator of a sample's length i.e. "11111111000000", in which case you should resample by a factor of the latter in order to minimize ambiguity

what the hell