Next.js 15 App Router Guide

Next.js 15 introduces several improvements to the App Router, making it even more powerful for building modern web applications. In this guide, we'll explore the key features and best practices.

Key Features in Next.js 15

1. Turbopack (Beta)

Next.js 15 includes an improved version of Turbopack, offering faster development compilation:

// next.config.ts
import { type Config } from "next";

const config: Config = {
  // Enable turbopack
  experimental: {
    turbo: true
  }
};

export default config;

2. Server Actions

Server Actions allow you to handle form submissions and data mutations directly in your components:

// app/actions.ts
'use server'

export async function submitForm(formData: FormData) {
  const name = formData.get('name')
  const email = formData.get('email')
  
  // Process the data
  await saveToDatabase({ name, email })
}

// app/page.tsx
import { submitForm } from './actions'

export default function Page() {
  return (
    <form action={submitForm}>
      <input name="name" type="text" />
      <input name="email" type="email" />
      <button type="submit">Submit</button>
    </form>
  )
}

3. Improved Metadata API

The new metadata API provides better SEO and social media optimization:

import { type Metadata } from 'next'

export const metadata: Metadata = {
  title: 'My Page',
  description: 'Page description',
  openGraph: {
    title: 'My Page',
    description: 'Page description',
    images: ['/og-image.jpg']
  }
}

Best Practices

1. Use TypeScript

   • Always define proper types for your props and API responses
   • Leverage TypeScript's type inference where possible

2. Implement Error Boundaries

   • Create error.tsx files in your app directory
   • Provide meaningful error messages and recovery options

3. Optimize Performance

   • Use React Server Components by default
   • Implement proper loading states with loading.tsx
   • Utilize image optimization with next/image

Conclusion

Next.js 15's App Router provides a robust foundation for building modern web applications. By following these best practices and leveraging the new features, you can create performant, type-safe, and maintainable applications.

Stay tuned for more in-depth tutorials on specific Next.js features!