Crazy!! I think that all the solutions which have been approved can easily be compiled into a library.
Fun to do, but a lot to write. In a few words: the best way to befriend your debugger.

One shall love recursion :D

What a struggle :)) Thanks for it! :)

Nice one! Very work-related. Thank you! :)

Great solution! Very OOP. Thank you!

Tricky one :P But now I can finally say that I have improved my relationship with debugger. Thanks! ^^

I will leave this for whoever may need it:

number_dict = {1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight', 9: 'nine',
               10: 'ten',
               11: 'eleven', 12: 'twelve', 13: 'thirteen', 14: 'fourteen', 15: 'fifteen', 16: 'sixteen',
               17: 'seventeen', 18: 'eighteen', 19: 'nineteen',
               20: 'twenty', 30: 'thirty', 40: 'forty', 50: 'fifty', 60: 'sixty', 70: 'seventy', 80: 'eighty',
               90: 'ninety', 100: 'hundred', 1000: 'thousand'}

Such a fun one! Thanks xD

Nice one! :) With this occasion, I have just learned a little bit of Regex in JavaScript :D :D

Funny one! :) A little bit trickier than it seems.

Thank you very much for this series! With this occasion, I polished my JavaScript skills and I think I am ready to approach more difficult katas. Greeeeeeat lesson! :D

NUMS = ['Zero', 'One', 'Two', 'Three', 'Four', 'Five', 'Six', 'Seven', 'Eight', 'Nine', 'Ten',
'Eleven', 'Twelve', 'Thirteen', 'Fourteen', 'Fifteen', 'Sixteen', 'Seventeen', 'Eighteen', 'Nineteen', 'Twenty']

to_19 = { 1 : "One", 2 : "Two", 3 : "Three", 4 : "Four", 5 : "Five",
6 : "Six", 7 : "Seven", 8 : "Eight", 9 : "Nine", 10 : "Ten",
11 : "Eleven", 12 : "Twelve", 13 : "Thirteen", 14 : "Fourteen",
15 : "Fifteen", 16 : "Sixteen", 17 : "Seventeen", 18 : "Eighteen",
19 : "Nineteen" }

Haha, cu placere :)

Merly math skills than programming skills, but nice one. It took me some time untill the bell rang.