Unit 2 Lesson 6 Challenge - Grokking

function getTokens(rawString) {
  // NB: `.filter(Boolean)` removes any falsy items from an array
  return rawString.toLowerCase().split(/[ ,!.";:-]+/).filter(Boolean).sort();
}

function mostFrequentWord(text) {
  // get words that have been sorted with spaces and non-alphabet characters removed
  var words = getTokens(text);
  var wordFrequencies = {};
  // add word in words and initialize count starting from 1 to each word not in the wordFrequencies object. If the word already exists in object, then simply add to the count.
  for (var i = 0; i <= words.length; i++) {
    if (words[i] in wordFrequencies) {
      wordFrequencies[words[i]]++;
    }
    else {
      wordFrequencies[words[i]]=1;
    }
  }
  // get the first the word and count from wordFrequencies object
  var currentMaxKey = Object.keys(wordFrequencies)[0];
  // get the count of the selected word
  var currentMaxCount = wordFrequencies[currentMaxKey];
  
  // loop through all the wordFrequencies objects, and if the word has more count than the current count of the selected word, change the selected word to the word that has more count, and then change the selected count to the count corresponding to the word
  for (var word in wordFrequencies) {
    if (wordFrequencies[word] > currentMaxCount) {
      currentMaxKey = word;
      currentMaxCount = wordFrequencies[word];
    }
  }
  // return the word with maximum count
  return currentMaxKey;
}