Suggestions for additional tests:

• Words with uppercase vowels with umlauts.
• Words with the German double-s (ß).
• Random words to prevent simple cheating.

Not if you care about readability.

THere is a problem with the current version of the testing framework.

In the code provided you have:

" Test.assertEqual(..."

This should instead be:

" Test.assertEquals(..."

I had more trouble interpreting the description that necessary. The: "counts how many nodes can be traversed from root without any child node having smaller value than its parent."

can be interpreted as
"find the longest non-decreasing chain from the root"

where the author actually means
"count the number of non-decreasing nodes reachable from the root".

Oh. To prevent cheating. Well. It is unfortunate that this is necessary.

Nice insightful kata. The current state of this Kata seems to be ready.

I find it to be a nice "aha"-moment when you realize it doesn't matter because sin(0)==sin(2PI)=sin(-2PI)=...

The description should specify the return value of the function:

Your task is to build a function "addWord" that appends a string to an array and returns the array:

addWord(object,string) -> object

Great with insigt into Array.prototype in error message. Thanks for the kata.

Perhaps make default code for the students to test with. This would make it clear how to use the scale input parameter.

Really good riddle. Thanks for putting it up as a kata.

• Description should read: "before the scale breaks"

• It should be clear that you can use the scales.weight property

• it should be clear that the pans should always be arrays - single numbers are not allowed.

The kata should make it clear that leftPan and rightPan only take arrays as values. Putting a single number in them returns an error.

Nice and compact solution.
Notice, however:
For a loop of size n and a tail of size m this algorithm runs in O((n+m)^2).

Inconsistency with description and expected code. The description mentions: "difference()" while the code expects "array_diff()"