Next.js

Dynamic APIs: Cookies, Headers & Draft Mode

28 min Lesson 46 of 80

Dynamic APIs: Cookies, Headers & Draft Mode

This lesson expands the Next.js path with an advanced topic from the official Next.js documentation. The goal is not only to memorize an option or file name, but to understand its impact on rendering, caching, security, and deployment.

After this lesson you should be able to apply the topic in a real project, choose the right boundary for it, and explain it as a reviewable engineering decision.

Core Concepts

async cookies
async headers
draftMode previews
runtime personalization
CMS preview flows

Practical Example

// app/blog/[slug]/page.tsx
import { draftMode } from 'next/headers'

export default async function Page({ params }: PageProps<'/blog/[slug]'>) {
  const { isEnabled } = await draftMode()
  const { slug } = await params
  const post = await getPostBySlug(slug, { preview: isEnabled })
  return <Article post={post} preview={isEnabled} />
}

This lesson is aligned with these official Next.js documentation areas: cookies, headers, draftMode, and dynamic API docs.

Why It Matters

In production applications, this topic affects page speed, data freshness, authorization clarity, and operational reliability after deployment.

Implementation Workflow

Decide whether the data is public or user-specific.
Choose the smallest part of the tree that needs this behavior.
Connect the example to a real route and add a small verification check.
Document the effect on caching and deployment.

Hands-on Practice

Implement a preview-aware blog page that shows draft content only for authorized editors.

Reading request APIs too high in the tree can force more rendering to be dynamic than necessary.

Summary

Judge the implementation by how clear the decision is, whether the behavior is correct after build, and how easily it can be traced in production.