1var assert = require('assert');
2
3/**
4 * Convert an integer to its words representation
5 *
6 * @author McShaman (http://stackoverflow.com/users/788657/mcshaman)
7 * @source http://stackoverflow.com/questions/14766951/convert-digits-into-words-with-javascript
8 */
9function numberToWords(n) {
10  var string = n.toString(),
11    units,
12    tens,
13    scales,
14    start,
15    end,
16    chunks,
17    chunksLen,
18    chunk,
19    ints,
20    i,
21    word,
22    words,
23    and = 'and';
24
25  /* Remove spaces and commas */
26  string = string.replace(/[, ]/g, '');
27
28  /* Is number zero? */
29  if (parseInt(string) === 0) {
30    return 'zero';
31  }
32
33  /* Array of units as words */
34  units = [
35    '',
36    'one',
37    'two',
38    'three',
39    'four',
40    'five',
41    'six',
42    'seven',
43    'eight',
44    'nine',
45    'ten',
46    'eleven',
47    'twelve',
48    'thirteen',
49    'fourteen',
50    'fifteen',
51    'sixteen',
52    'seventeen',
53    'eighteen',
54    'nineteen',
55  ];
56
57  /* Array of tens as words */
58  tens = [
59    '',
60    '',
61    'twenty',
62    'thirty',
63    'forty',
64    'fifty',
65    'sixty',
66    'seventy',
67    'eighty',
68    'ninety',
69  ];
70
71  /* Array of scales as words */
72  scales = [
73    '',
74    'thousand',
75    'million',
76    'billion',
77    'trillion',
78    'quadrillion',
79    'quintillion',
80    'sextillion',
81    'septillion',
82    'octillion',
83    'nonillion',
84    'decillion',
85    'undecillion',
86    'duodecillion',
87    'tredecillion',
88    'quatttuor-decillion',
89    'quindecillion',
90    'sexdecillion',
91    'septen-decillion',
92    'octodecillion',
93    'novemdecillion',
94    'vigintillion',
95    'centillion',
96  ];
97
98  /* Split user arguemnt into 3 digit chunks from right to left */
99  start = string.length;
100  chunks = [];
101  while (start > 0) {
102    end = start;
103    chunks.push(string.slice((start = Math.max(0, start - 3)), end));
104  }
105
106  /* Check if function has enough scale words to be able to stringify the user argument */
107  chunksLen = chunks.length;
108  if (chunksLen > scales.length) {
109    return '';
110  }
111
112  /* Stringify each integer in each chunk */
113  words = [];
114  for (i = 0; i < chunksLen; i++) {
115    chunk = parseInt(chunks[i]);
116
117    if (chunk) {
118      /* Split chunk into array of individual integers */
119      ints = chunks[i].split('').reverse().map(parseFloat);
120
121      /* If tens integer is 1, i.e. 10, then add 10 to units integer */
122      if (ints[1] === 1) {
123        ints[0] += 10;
124      }
125
126      /* Add scale word if chunk is not zero and array item exists */
127      if ((word = scales[i])) {
128        words.push(word);
129      }
130
131      /* Add unit word if array item exists */
132      if ((word = units[ints[0]])) {
133        words.push(word);
134      }
135
136      /* Add tens word if array item exists */
137      if ((word = tens[ints[1]])) {
138        words.push(word);
139      }
140
141      /* Add 'and' string after units or tens integer if: */
142      if (ints[0] || ints[1]) {
143        /* Chunk has a hundreds integer or chunk is the first of multiple chunks */
144        if (ints[2] || (!i && chunksLen)) {
145          words.push(and);
146        }
147      }
148
149      /* Add hundreds word if array item exists */
150      if ((word = units[ints[2]])) {
151        words.push(word + ' hundred');
152      }
153    }
154  }
155
156  return words.reverse().join(' ');
157}
158
159try {
160  assert.equal(numberToWords(1234), 'one thousand two hundred and thirty four');
161
162  console.log(
163    'PASSED: ' +
164      "assert.equal(numberToWords(1234), 'one thousand two hundred and thirty four');"
165  );
166} catch (err) {
167  console.log(err);
168}