Two letter words?

gistfile1.js

var alphabet = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"];
var vowels = ["a", "e", "i", "o", "u", "y", "h"];

var numberOfWords = 0;

var words = [];

var populatePossibilities = function(base) {
  var newPossibilities = [];
  var baseLength = base.length;
  for (var i=0; i < baseLength; i++) {
    for (var j=0; j < baseLength; j++) {
      newPossibilities.push(base[i] + base[j]);
    }
  }
  return newPossibilities;
};

var possibilities = populatePossibilities(alphabet);

var isVowel = function(testLetter, testVowels) {
  var vowelLength = testVowels.length;
  for (var i=0; i < vowelLength; i++) {
    if ( testVowels[i] === testLetter ) {
      return true;
    }
  }
  return false;
};

var isUnique = function(testWord, checkList) {
  var checkListLength = checkList.length;
  for (var i=0; i < checkListLength; i++) {
    if ( checkList[i] === testWord ) {
      return false;
    }
  }
  return true;
};

var checkStrings = function(wordsArray, testVowels) {

  var wordsLength = wordsArray.length;
  for (var i=0; i < wordsLength; i++) {

    if ( isUnique(wordsArray[i], words) ) {

      var stringAsArray = wordsArray[i].split("");
      if ( isVowel(stringAsArray[0], testVowels) || isVowel(stringAsArray[1], testVowels) ) {
        numberOfWords++;
        words.push(wordsArray[i]);
      };

    }

  }

  return words;

};

checkStrings(possibilities, vowels);