completed 4.5

parts/4/blogApp/src/utils.js

@@ -27,9 +27,25 @@ const totalLikes = (posts) => {
   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,
 };

parts/4/blogApp/tests/favoritePost.test.js

@@ -0,0 +1,43 @@
+const { test, describe } = require("node:test");
+const assert = require("node:assert");
+const { favoritePost } = require("../src/utils");
+
+describe("favoritePost ", () => {
+  const posts = [
+    {
+      _id: "5a422aa71b54a676234d17f8",
+      title: "Go To Statement Considered Harmful",
+      author: "Edsger W. Dijkstra",
+      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
+      likes: 5,
+      __v: 0,
+    },
+    {
+      _id: "5a422aa71b54a676234d17f8",
+      title: "Go To Statement Considered Harmful",
+      author: "Edsger W. Dijkstra",
+      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
+      likes: 2,
+      __v: 0,
+    },
+  ];
+
+  const emptyArray = [];
+
+  const gibberish = "asdaSd123asd";
+
+  test("finds top properly", () => {
+    assert.strictEqual(favoritePost(posts), posts[0]);
+  });
+
+  test("works fine with empty array", () => {
+    assert.strictEqual(favoritePost(emptyArray), null);
+  });
+
+  test("fails with gibberish input", () => {
+    const failedCall = () => {
+      favoritePost(gibberish);
+    };
+    assert.throws(failedCall, Error);
+  });
+});

parts/4/notes.md

@@ -3,4 +3,4 @@ Exercises:
 * [X] 4.2
 * [X] 4.3
 * [X] 4.4
-* 
+* [X] 4.5