feat: improve slug page perf

app/posts/[slug]/actions.test.ts

@@ -1,11 +1,8 @@
-import * as postsActions from '../actions'
-
-import { fetchPostBySlug, fetchPreviousPost } from './actions'
+import { fetchPostBySlug } from './actions'
 
 import * as mdx from '@/lib/mdx'
 import type { Post } from '@/lib/types'
 import { getMockFrontmatter } from '@/test/mocks/frontmatter'
-import { getMockSource } from '@/test/mocks/source'
 
 vi.mock('@/lib/mdx')
 vi.mock('../actions')
@@ -56,26 +53,4 @@ describe('/posts/[slug]/actions', () => {
       })
     })
   })
-
-  describe('fetchPreviousPost', () => {
-    const mockPosts: Post[] = [
-      { slug: 'slug-1', ...getMockFrontmatter(), source: getMockSource() },
-      { slug: 'slug-2', ...getMockFrontmatter(), source: getMockSource() },
-    ]
-
-    it('returns the next index of results returned from fetchPublishedPosts()', async () => {
-      vi.mocked(postsActions.fetchPublishedPosts).mockResolvedValue(mockPosts)
-
-      const actual = await fetchPreviousPost('slug-1')
-      expect(actual).toBeTruthy()
-      expect(actual?.slug).toEqual('slug-2')
-    })
-
-    it('returns undefined when the bottom of the list is reached', async () => {
-      vi.mocked(postsActions.fetchPublishedPosts).mockResolvedValue(mockPosts)
-
-      const actual = await fetchPreviousPost('slug-2')
-      expect(actual).toBeUndefined()
-    })
-  })
 })

app/posts/[slug]/actions.ts

@@ -4,8 +4,6 @@ import path from 'path'
 
 import { notFound } from 'next/navigation'
 
-import { fetchPublishedPosts } from '../actions'
-
 import { getPostFromMDX } from '@/lib/mdx'
 import type { Post } from '@/lib/types'
 
@@ -22,12 +20,3 @@ export async function fetchPostBySlug(slug: string): Promise<Post> {
     }
   }
 }
-
-export async function fetchPreviousPost(slug: string): Promise<Post | undefined> {
-  const publishedPosts = await fetchPublishedPosts()
-  const postIndex = publishedPosts.findIndex((post) => post.slug === slug)
-
-  if (postIndex === publishedPosts.length - 1) return undefined
-
-  return publishedPosts[postIndex + 1]
-}

app/posts/[slug]/page.tsx

@@ -1,12 +1,11 @@
-import { ChevronLeft, ChevronRight } from 'lucide-react'
-import { Metadata } from 'next'
+import { ChevronLeft } from 'lucide-react'
+import { type Metadata } from 'next'
 import Image from 'next/image'
 import Link from 'next/link'
 
 import { fetchPublishedPosts } from '../actions'
 
-import { fetchPostBySlug, fetchPreviousPost } from './actions'
-import MDXContent from './mdx-content'
+import { fetchPostBySlug } from './actions'
 import TimeInformation from './time-information'
 
 import { Tag } from '@/components/tag'
@@ -19,11 +18,13 @@
 export async function generateStaticParams() {
   const publishedPosts = await fetchPublishedPosts()
 
-  return publishedPosts.map((post) => ({
-    slug: post.slug,
+  return publishedPosts.map(({ slug }) => ({
+    slug,
   }))
 }
 
+export const dynamicParams = false
+
 export const generateMetadata = async ({ params }: { params: Promise<{ slug: string }> }): Promise<Metadata> => {
   const { slug } = await params
   const post = await fetchPostBySlug(slug)
@@ -50,13 +51,14 @@
 export default async function PostPage({ params }: { params: Promise<{ slug: string }> }) {
   const { slug } = await params
   const post = await fetchPostBySlug(slug)
-  const previousPost = await fetchPreviousPost(slug)
+
+  const { default: Post } = await import(`@/posts/${slug}.mdx`)
 
   return (
     <div className="mx-0 my-10 flex flex-col items-center md:mx-20">
       <AspectRatio ratio={16 / 9}>
         <Image src={post.thumbnail} alt="Article cover image" className="rounded-xl border-2" priority fill />
       </AspectRatio>
       <TypographyH1>{post.title}</TypographyH1>
       <div className="flex w-full flex-col items-center gap-4">
         <span className="flex flex-row flex-wrap gap-2">
@@ -67,22 +69,13 @@
         <TimeInformation metadata={{ publishedAt: post.publishedAt, source: post.source }} />
       </div>
       <article className="mt-8">
-        <MDXContent source={post.source} />
+        <Post />
       </article>
       <div className="border-color mt-8 flex w-full flex-row justify-center gap-4 border-t pt-8">
         <Link href="/posts" className={cn(buttonVariants({ variant: 'outline' }), 'w-2/5 md:w-1/2')}>
           <ChevronLeft width={16} height={16} />
           &nbsp;All posts
         </Link>
-        {!!previousPost && (
-          <Link
-            href={`/posts/${previousPost.slug}`}
-            className={cn(buttonVariants({ variant: 'outline' }), 'w-2/5 md:w-1/2')}
-          >
-            <ChevronRight width={16} height={16} />
-            &nbsp;Next
-          </Link>
-        )}
       </div>
     </div>
   )

mdx-components.tsx

@@ -0,0 +1,39 @@
+import type { MDXComponents } from 'mdx/types'
+import Image, { type ImageProps } from 'next/image'
+import type { HTMLAttributes, PropsWithChildren } from 'react'
+
+export function useMDXComponents(components: MDXComponents): MDXComponents {
+  return {
+    ...{
+      img: (props: HTMLAttributes<HTMLImageElement>) => (
+        <Image
+          {...(props as ImageProps)}
+          alt="article image"
+          className="my-4 aspect-video rounded-lg object-center"
+          width={1600}
+          height={900}
+        />
+      ),
+      h1: (props: PropsWithChildren) => <h1 className="prose my-8 text-4xl font-semibold md:my-12" {...props} />,
+      h2: (props: PropsWithChildren) => <h2 className="prose my-6 text-3xl font-semibold md:my-8" {...props} />,
+      h3: (props: PropsWithChildren) => <h3 className="prose my-6 text-2xl font-semibold md:my-8" {...props} />,
+      p: (props: PropsWithChildren) => <h4 className="text-normal w-prose my-2 font-normal" {...props} />,
+      ol: (props: PropsWithChildren) => <ol className="my-6 ml-6 list-decimal [&>li]:mt-2" {...props} />,
+      ul: (props: PropsWithChildren) => <ul className="my-6 ml-6 list-disc [&>li]:mt-2" {...props} />,
+      blockquote: (props: PropsWithChildren) => <blockquote className="my-6 border-l-2 pl-6 italic" {...props} />,
+      code: (props: PropsWithChildren) => (
+        <code
+          className="bg-muted relative rounded-lg px-[0.3rem] py-[0.2rem] font-mono text-sm font-semibold"
+          {...props}
+        />
+      ),
+      pre: ({ className, ...rest }: HTMLAttributes<HTMLElement>) => (
+        <pre className="my-5 whitespace-pre-wrap [&>code:nth-child(1)]:p-3" {...rest} />
+      ),
+      a: (props: PropsWithChildren) => (
+        <a className="text-md text-primary/75 p-0 underline underline-offset-2" {...props} />
+      ),
+    },
+    ...components,
+  }
+}

next.config.ts

@@ -0,0 +1,59 @@
+import createMDX from '@next/mdx'
+import { type NextConfig } from 'next'
+import rehypeAutolinkHeadings from 'rehype-autolink-headings'
+import rehypePrettyCode from 'rehype-pretty-code'
+import rehypeSlug from 'rehype-slug'
+import remarkFrontmatter from 'remark-frontmatter'
+import remarkGfm from 'remark-gfm'
+import remarkMdxFrontmatter from 'remark-mdx-frontmatter'
+import { type HighlighterCoreOptions, getSingletonHighlighter } from 'shiki'
+
+const nextConfig: NextConfig = {
+  reactStrictMode: true,
+  images: {
+    remotePatterns: [],
+  },
+  transpilePackages: ['next-mdx-remote'],
+  pageExtensions: ['md', 'mdx', 'ts', 'tsx'],
+  async rewrites() {
+    return [
+      {
+        source: '/ingest/static/:path*',
+        destination: 'https://us-assets.i.posthog.com/static/:path*',
+      },
+      {
+        source: '/ingest/:path*',
+        destination: 'https://us.i.posthog.com/:path*',
+      },
+    ]
+  },
+  // ? NOTE: This is required to support PostHog trailing slash API requests
+  skipTrailingSlashRedirect: true,
+}
+
+const withMDX = createMDX({
+  extension: /\.(md|mdx)$/,
+  options: {
+    remarkPlugins: [remarkGfm, remarkFrontmatter, remarkMdxFrontmatter],
+    rehypePlugins: [
+      rehypeSlug,
+      rehypeAutolinkHeadings,
+      [
+        rehypePrettyCode,
+        {
+          theme: 'one-dark-pro',
+          keepBackground: false,
+          getHighlighter: (options: HighlighterCoreOptions) => {
+            return getSingletonHighlighter({
+              ...options,
+              themes: ['one-dark-pro'],
+              langs: ['js', 'ts', 'jsx', 'tsx', 'json', 'json5', 'shell', 'bash', 'astro', 'markdown'],
+            })
+          },
+        },
+      ],
+    ],
+  },
+})
+
+export default withMDX(nextConfig)

package.json

@@ -13,7 +13,10 @@
     }
   },
   "lint-staged": {
-    "*.{ts,tsx}": ["next lint --fix", "pnpm format"],
+    "*.{ts,tsx}": [
+      "next lint --fix",
+      "pnpm format"
+    ],
     "*.md": "prettier --list-different"
   },
   "scripts": {
@@ -39,6 +42,9 @@
     "typecheck": "tsc --pretty"
   },
   "dependencies": {
+    "@mdx-js/loader": "3.1.0",
+    "@mdx-js/react": "3.1.0",
+    "@next/mdx": "15.3.5",
     "@radix-ui/react-accordion": "1.2.11",
     "@radix-ui/react-aspect-ratio": "1.1.7",
     "@radix-ui/react-avatar": "1.1.10",
@@ -56,15 +62,13 @@
     "geist": "1.4.2",
     "lucide-react": "0.511.0",
     "next": "15.3.3",
-    "next-mdx-remote": "5.0.0",
     "next-themes": "0.4.6",
     "posthog-js": "1.255.0",
     "posthog-node": "4.17.2",
     "react": "19.1.0",
     "react-dom": "19.1.0",
     "rss": "1.2.2",
     "sharp": "0.34.2",
-    "shiki": "3.4.2",
     "tailwind-merge": "3.3.1"
   },
   "devDependencies": {
@@ -74,9 +78,11 @@
     "@next/eslint-plugin-next": "15.3.4",
     "@playwright/test": "1.53.0",
     "@tailwindcss/postcss": "4.1.11",
+    "@tailwindcss/typography": "0.5.16",
     "@testing-library/jest-dom": "6.6.3",
     "@testing-library/react": "16.3.0",
     "@testing-library/user-event": "14.6.1",
+    "@types/mdx": "2.0.13",
     "@types/node": "22.7.5",
     "@types/react": "19.1.8",
     "@types/react-dom": "19.1.5",
@@ -104,7 +110,10 @@
     "rehype-autolink-headings": "7.1.0",
     "rehype-pretty-code": "0.14.1",
     "rehype-slug": "6.0.0",
+    "remark-frontmatter": "5.0.0",
     "remark-gfm": "4.0.1",
+    "remark-mdx-frontmatter": "5.2.0",
+    "shiki": "3.4.2",
     "tailwindcss": "4.1.10",
     "tailwindcss-animate": "1.0.7",
     "tw-animate-css": "1.3.0",