consolidate mdx file parsing

pages/notes/index.tsx

@@ -1,23 +1,29 @@
+import { format } from "date-fns";
 import Layout from "../../components/Layout";
 import Container from "../../components/Container";
 import List from "../../components/notes/List";
 import { getAllNotes } from "../../lib/parse-notes";
 import type { GetStaticProps } from "next";
 
-const Notes = ({ notes }) => (
+const Notes = ({ notesByYear }) => (
   <Layout>
     <Container title="Notes" description="Recent posts by Jake Jarvis.">
-      <List notes={notes} />
+      <List notesByYear={notesByYear} />
     </Container>
   </Layout>
 );
 
 export const getStaticProps: GetStaticProps = async () => {
-  const notes = getAllNotes();
+  // parse the year of each note and group them together
+  const notesByYear = {};
+  getAllNotes().map((note) => {
+    const year = parseInt(format(new Date(note.date), "yyyy"));
+    (notesByYear[year] || (notesByYear[year] = [])).push(note);
+  });
 
   return {
     props: {
-      notes,
+      notesByYear,
     },
   };
 };