refactor: 改用 TypeScript。close #1.

lib/utils/formatDate.ts

@@ -0,0 +1,14 @@
+import siteMetadata from '@/data/siteMetadata'
+
+const formatDate = (date: string) => {
+  const options: Intl.DateTimeFormatOptions = {
+    year: 'numeric',
+    month: 'long',
+    day: 'numeric',
+  }
+  const now = new Date(date).toLocaleDateString(siteMetadata.locale, options)
+
+  return now
+}
+
+export default formatDate