GrokkingDrill.js

function getTokens(rawString) {
  // NB: `.filter(Boolean)` removes any falsy items from an array
  // method '.toLowerCase' makes all the characters in the string 'rawString' smallcaps
  // method '.split' splits each item in the string with the characters passed 
  // method '.sort()' will sort the string alphabetically
  return rawString.toLowerCase().split(/[ ,!.";:-]+/).filter(Boolean).sort();
}
  
function mostFrequentWord(text) {
  // locally creating a variable 'words' that calls the function getTokens passing the argument on this function
  var words = getTokens(text);
  // creating a variable 'wordFrequencies' thats an object
  var wordFrequencies = {};
  // loop that iterates thru the length of 'words' variable, at this point it understands that 'getTokens' function
  // produces an array
  for (var i = 0; i <= words.length; i++) {
    // logic that accesses 'i' position in array and states 'if 'i'position in words is 'in' wordFrequencies
    if (words[i] in wordFrequencies) {
      // then the key in wordFrequencies 'words[i]' increments and this is what marks how frequent the word is showing
      wordFrequencies[words[i]]++;
    }
    // otherwise the key in wordFrequencies 'words[i]' equals 1 so its not repeating in the object
    else {
      wordFrequencies[words[i]]=1;
    }
  }
  // this var states that the current max repetitions of keys or words is 0
  var currentMaxKey = Object.keys(wordFrequencies)[0];
  // this var is equivalent to the key 'currentMaxKey' in wordFrequencies
  var currentMaxCount = wordFrequencies[currentMaxKey];
  
  // this loop is gonna continue looking for the 'word' in wordFrquencies
  for (var word in wordFrequencies) {
    // if the word in wordFrequencies is greater than the currentMaxCount
    if (wordFrequencies[word] > currentMaxCount) {
      // then assign that word as the amount of times
      currentMaxKey = word;
      // and current max count to that word so it doesnt count it again and can move on to next
      currentMaxCount = wordFrequencies[word];
    }
  }
  return currentMaxKey;
}