Great kata, I really liked it

CoffeeScript translation

Already fixed by the author

Fixed

Updated

I think you misunderstood my comment. An array of digits would be ['7', '8', '9'], because digits are characters. An array of single digits numbers would be [7, 8, 9]. I think you want the latter.

A digit is a single character representing the symbol [0-9]. 289 is not a digit, it's a number that consists of 3 digits. Therefore,[12,156,111,568] is not an array of digits, it's an array of numbers. "array of single digits numbers" would be redundant.

• Python new test framework should be used (Refer this & this for more detail)

Haskell translation

JS : the tests should use assert.deepEqual, through chai, not Test.assertSimilar

The tests shouldn't log anything in JavaScript.

Not kata-related.

Digits are characters, but with a little goodwill one could read "digit" to mean "single digit non-negative number". I'd prefer making it precise.

Well, the reference solution would fail too (at least in javascript), so, I think it's better if description is changed instead.

in an array of digits

Could it be read "array of single digits numbers"?

There is nothing in the description that says that the array contains single digit numbers only. Add a test with [78, 9] as input, and you'll see many so called "solutions" fail.