Number to Words (Coffeescript)

number_to_words.coffee

NAMES = ['hundred', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quattuordecillion', 'quindecillion', 'sexdecillion', 'septendecillion', 'octodecillion', 'novemdecillion', 'vigintillion']
WORDS = { '0': '', '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': 'forteen', '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' }

to_words = (number) ->
  number = number.toString()
  string = if (number.replace('-', '') == number) then '' else 'negative'
  number = number.replace('-', '')
  number = '0' + number while (number.length % 3 != 0)
  triplets = number.match(/.../g)

  for triplet, index in triplets
    string += ' ' + WORDS[triplet[0]] + (if triplet[0] == '0' then '' else " #{NAMES[0]}") if triplet.length == 3
    string += if (triplet[1] + triplet[triplet.length - 1]) of WORDS then (' ' + WORDS[triplet[1] + triplet[triplet.length - 1]]) else (' ' + WORDS[(parseInt(triplet[1]) * 10).toString()] + ' ' + WORDS[triplet[triplet.length - 1]])
    string += ' ' + NAMES[triplets.length - index - 1] unless index + 1 == triplets.length

  string.replace(/\s+/g, ' ')

# Largest supported integer is 2^53. Anything larger should be passed as a string
# console.log to_words "-123456"
console.log to_words "-123456789012345678901234567890123456789012345678901234567890"