// takes a string as input and returns an array of all words in the string, stripping non-alphanumeric characters
function getTokens(rawString) {
  // NB: `.filter(Boolean)` removes any falsy items from an array
  return rawString.toLowerCase().split(/[ ,!.";:-]+/).filter(Boolean).sort();
}

// takes in a string of text, and returns a string representation of the most frequently occuring word in that string
function mostFrequentWord(text) {
  // assigns variable referring to array of words in string
  let words = getTokens(text);
  // declares an empty obj to store word counts
  let wordFrequencies = {};
  // iterates over words in array. for each word, if the word is present in the frequency object, the value is incremented; otherwise
  // it adds the word as a key with a value of 1
  for (let i = 0; i <= words.length; i++) {
    if (words[i] in wordFrequencies) {
      wordFrequencies[words[i]]++;
    } else {
      wordFrequencies[words[i]] = 1;
    }
  }

  // declares variables to track the highest frequency word; intially set to the first key in the array of the frequency object's keys
  let currentMaxKey = Object.keys(wordFrequencies)[0];
  let currentMaxCount = wordFrequencies[currentMaxKey];

  // iterates over keys in wordFrequencies object. if the value (count) of that key is greater than the current max, the key
  // replaces the currentMaxKey, and the value replaces the currentMaxCount
  for (let word in wordFrequencies) {
    if (wordFrequencies[word] > currentMaxCount) {
      currentMaxKey = word;
      currentMaxCount = wordFrequencies[word];
    }
  }
  // You wanted a word!? Well, here's a word! The most frequent word! The best word!
  return currentMaxKey;
}