! is a regular character in JS regex, but ? is a special character (the "zero or one" quantifier in this specific instance) which has to be escaped.

/!/g how did it work without scaping like this /?/g

your solution upvoted (clever + 1)

Thanks a lot! Fixed!

Probably a (O²) algorithm will not pass the tests

Complexity notation doesn't work like that, it should be O(n²).

Thanks for your solution, upvoted (clever +1)

countourMode = countTourMode, it should be :)

The function name is misspelled in JS (should be contourMode).

Just think about 1000 bottles of whine.

LOL. I suppose the King can store them in the palace cellar along with his 50 barrels of grizzle, 20 tubs of whinge, and that giant vat of moan that nobody wants to go near...

:-)

You are right.
it was only in the python translation - now it's fixed.
thanks.

The ECMAScript standard doesn't specify and V8 (NodeJS, Chromium) doesn't guarantee stability, so this is expected.

However, the longer random examples in this Kata appeared to break this pattern, and equivalent length strings were rearranged in the array after the sort method. I'm not able to explain this behaviour.

I haven't looked at the source, so I'm just guessing, but probably the sorting algorithm used depends on the length of the array. Switching to unstable but faster one for larger array.

['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'].sort((a, b) => a.length - b.length);
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']

['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a'].sort((a, b) => a.length - b.length);
['5', '0', '2', '3', '4', '1', '6', '7', '8', '9', 'a']

Looks like in-place quicksort and insertion sort is used (v8/src/js/array.js#L709-L1002).

// Insertion sort is faster for short arrays.
if (to - from <= 10) {
  InsertionSort(a, from, to);
  return;
}

Interesting Kata. I've discovered a quirk about the javacript Array.prototype.sort method, that sometimes re-arranges array items in an unexpected fashion. For example, when implementing the following code, the expected result is returned.

['abc', 'def', 'ghi'].sort((a, b) => a.length - b.length).join('') // => 'abcdefghi'

However, the longer random examples in this Kata appeared to break this pattern, and equivalent length strings were rearranged in the array after the sort method. I'm not able to explain this behaviour.