fullstackopen-notes/parts/4/blogApp/src/utils.js

const reverse = (string) => {
  return string.split("").reverse().join("");
};

const average = (array) => {
  const reducer = (sum, item) => {
    return sum + item;
  };

  return array.length === 0 ? 0 : array.reduce(reducer, 0) / array.length;
};

const listHelper = (posts) => {
  console.log("lol");
  return 1;
};

const totalLikes = (posts) => {
  if (!posts) {
    return 0;
  }

  const likeCount = posts
    .map((post) => post.likes)
    .reduce((cum, value) => cum + value, 0);

  return likeCount;
};

const favoritePost = (posts) => {
  if (!posts || posts.length === 0) {
    return null;
  }

  const highestLikes = posts.reduce(
    (max, post) => (post.likes > max ? (max = post.likes) : max),
    0
  );

  const favoritePost = posts.find((post) => post.likes == highestLikes);

  return favoritePost;
};

module.exports = {
  reverse,
  average,
  listHelper,
  totalLikes,
  favoritePost,
};