T9 Dictionary for node.js

t9Dictionary.js

// Usage:
// var T9Dictionary = require('./t9_dictionary')
// var dict = new T9Dictionary(<path to text file>)
// dict.suggest(4663) =>  [ 'good', 'gone', 'home', 'hood', 'hoof' ]

module.exports = (function () {

  // Modules
  var fs = require('fs');

  var _dictionary = {},
      _phoneLetters = {
        a: 2, b: 2, c: 2, d: 3, e: 3, f: 3, g: 4, h: 4, i: 4,
        j: 5, k: 5, l: 5, m: 6, n: 6, o: 6, p: 7, q: 7, r: 7,
        s: 7, t: 8, u: 8, v: 8, w: 9, x: 9, y: 9, z: 9
      };

  // Helper Functions:

  // Phone spelling of a word ('home' => '4663')
  function phoneSpelling (word) {
    if (/[^a-z]/.test(word)) return; // return if contains non letters
    return word.replace(/[a-z]/g, function (c) { return _phoneLetters[c]; } );
  }

  function T9Dictionary (dictFile) {
    if (dictFile) this.loadDictionary(dictFile);
  }

  T9Dictionary.prototype = {

    // Reinstates overwritten constructor
    constructor: T9Dictionary,

    // Load all the words in _dictionary
    loadDictionary: function (file) {
      fs.readFile(file, 'utf-8', function (err, content) {
        if (err) throw err;

        var wordCount, phoneWord, word,
            words = content.toLowerCase().split(/\s+/);

        // extracting/counting words:
        // => { '4663': { 'home': 3, <word>: <count> } }
        for (var i = 0; i < words.length; i++) {
          word = words[i];
          if (phoneWord = phoneSpelling(word)) {
            _dictionary[phoneWord]        = _dictionary[phoneWord] || {};
            _dictionary[phoneWord][word]  = _dictionary[phoneWord][word] || 0;
            _dictionary[phoneWord][word] += 1;
          }
        }

        // translating hashes to sorted arrays:
        // => { '4663': [ [<words with count less than 3>], ['home', <other words that repeat 3 times>] ] }
        for (var phnWrd in _dictionary) {
          var wordArr = [];
          // first transfer keys to values
          for (var wrd in _dictionary[phnWrd]) {
            wordCount = _dictionary[phnWrd][wrd];
            wordArr[wordCount] = wordArr[wordCount] || [];
            wordArr[wordCount].push(wrd);
          }
          
          // clear empty vals from array (TODO: there must be a better way)
          _dictionary[phnWrd] = wordArr.filter(function () { return true; });   
        }

        console.log('Dictionary loaded successfully');

      });
    },

    // Suggests <count> words based on <phoneNums>
    suggest: function (phoneNums, count) {
      count = count || 5;
      var words = _dictionary[phoneNums] || [],
          topWords = [];

      for (var i = words.length - 1; topWords.length < count && i >= 0; i--) {
        topWords = topWords.concat(words[i]);
      }

      return topWords.slice(0, count);
    }
  };

  return T9Dictionary;

})();

Ah clever I never even considered turning existing dictionary words into their phone number equivalent!