highestScoringWord.js

const wordList = ["apple", "cherry", "banana", "grape"];

const letterValues = [...Array(26).keys()].reduce((scores, number) => {
  scores[String.fromCharCode(97 + number)] = number + 1;
  return scores;
}, {}); // {a: 1, b: 2, c: 3 ...}

const calculateWordScore = (word) => {
  return word
    .toLowerCase()
    .split("")
    .reduce((total, letter) => {
      total += letterValues[letter];
      return total;
    }, 0);
};

const wordScores = wordList.reduce((totalsArray, word) => {
  totalsArray.push(calculateWordScore(word));
  return totalsArray;
}, []);

const highestScoringWord = (wordList, wordScores) => {
  if (wordList.length === 0) return;
  const wordIndex = wordScores.indexOf(Math.max(...wordScores));
  return wordList[wordIndex];
};

module.exports = {
  wordList,
  letterValues,
  wordScores,
  calculateWordScore,
  highestScoringWord
};

highestScoringWord.js.test.js

const { wordList, letterValues, calculateWordScore, wordScores, highestScoringWord } = require("./highestScoringWord.js");

describe("Word Scoring Test, let's gooooo", () => {
  test("letterValues should have 26 items", () => {
    expect(Object.keys(letterValues).length).toBe(26);
  });

  test("calculateWordScore should calculate correctly for a single word", () => {
    expect(calculateWordScore("Cassidy")).toBe(80);
  });

  test("wordScores should produce an array with the same amount of items as wordList", () => {
    expect(wordScores.length).toEqual(wordList.length);
  });

  test("highestScoringWord should return... the highest scoring word", () => {
    expect(highestScoringWord(wordList, wordScores)).toBe("cherry");
  });

  test("highestScoringWord should handle an empty word list with poise and grace", () => {
    expect(highestScoringWord([], wordScores)).toBe(undefined);
  });
});