project-2.6.6.js

// discussed when used in mostFrequentWord
function getTokens(rawString) {
  // NB: `.filter(Boolean)` removes any falsy items from an array
  return rawString.toLowerCase().split(/[ ,!.";:-]+/).filter(Boolean).sort();
}
  
function mostFrequentWord(text) {
  var words = getTokens(text);              // splits text by spaces and punctuation into array of words (strings), removes empty strings and sorts
  var wordFrequencies = {};                 // declare variable and initialise with empty object, this is used as a frequency counter
  for (var i = 0; i <= words.length; i++) { // loop over words
    if (words[i] in wordFrequencies) {      // if the current word already exists in the wordFrequencies object
      wordFrequencies[words[i]]++;          // increment its count
    }
    else {                                  // otherwise
      wordFrequencies[words[i]]=1;          // add the new word to the wordFrequencies counter and set it's value to one
    }
  }
  var currentMaxKey = Object.keys(wordFrequencies)[0];  // initialise the cuurent max key to the first word
  var currentMaxCount = wordFrequencies[currentMaxKey]; // and the associate count of the first word recorded as the current max
  
  for (var word in wordFrequencies) {                   // for all words counted
    if (wordFrequencies[word] > currentMaxCount) {      // if the frequency count of the current word is greater than the current max
      currentMaxKey = word;                             // set the key of the current word as the new current max
      currentMaxCount = wordFrequencies[word];          // along with its frequency count
    }
  }
  return currentMaxKey;                                 // return the key of the word with the greatest frequency in the text
}