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Next.js

Next.js App Router vs. Pages Router Explained

By Filip on 10/05/2024

This article explores the key differences between App Router and Pages Router in Next.js, empowering developers to choose the optimal routing solution for their applications.

Next.js App Router vs. Pages Router Explained

Table of Contents

Introduction

This article delves into the two primary routing methods offered by Next.js: the App Router and the Pages Router. It emphasizes the importance of understanding their differences to make an informed decision for your project. The article covers key aspects such as file-based routing, data fetching techniques, layout management, and SEO considerations. Code examples in JavaScript illustrate the implementation of both routers. Ultimately, the article guides you in choosing the appropriate router based on your project's specific requirements and priorities.

Step-by-Step Guide

Next.js offers two primary routing methods: the App Router (new in Next.js 13) and the Pages Router (the traditional approach). Understanding their differences is crucial for choosing the right one for your project.

1. File-Based Routing:

  • Pages Router: Relies on file structure within the pages directory. Each file represents a route, making it intuitive and easy to grasp.
  • App Router: Introduces a more flexible structure using the app directory. Nested layouts and components define routes, offering greater control over UI composition.

2. Data Fetching:

  • Pages Router: Primarily uses getServerSideProps or getStaticProps for data fetching. These functions run on the server, providing SEO benefits but potentially impacting performance.
  • App Router: Leverages React's Suspense for data fetching, enabling efficient loading states and smoother user experiences. It supports both server-side and client-side data fetching with fetch or libraries like swr.

3. Layouts:

  • Pages Router: Requires manual layout management using components or libraries.
  • App Router: Offers built-in layout support through nested components within the app directory. This simplifies creating consistent layouts across different parts of your application.

4. SEO Considerations:

  • Pages Router: Generally considered better for SEO due to server-side rendering and clear file-based routing.
  • App Router: While still capable of good SEO, it requires careful consideration of data fetching strategies and potential client-side rendering implications.

5. Code Example (JavaScript):

Pages Router:

// pages/index.js
export default function Home() {
  return <h1>Welcome to the home page!</h1>;
}

// pages/about.js
export default function About() {
  return <h1>About us</h1>;
}

App Router:

// app/page.js
export default function Home() {
  return <h1>Welcome to the home page!</h1>;
}

// app/about/page.js
export default function About() {
  return <h1>About us</h1>;
}

// app/layout.js
export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        <header>My App</header>
        {children}
      </body>
    </html>
  );
}

Choosing the Right Router:

  • Pages Router: Ideal for simpler projects, content-focused websites, and situations where SEO is a top priority.
  • App Router: Suitable for complex applications, highly interactive experiences, and when you need fine-grained control over UI composition and data fetching.

Remember: Both routers have their strengths and weaknesses. Carefully evaluate your project's needs and priorities to make the best choice.

Code Example

This code showcases the differences between Next.js's App Router and Pages Router using JavaScript examples. The Pages Router example demonstrates data fetching at build time with getStaticProps for static content. The App Router example highlights server-side data fetching with async/await and introduces nested layouts for consistent page structure. Key considerations include error handling, loading states, and client-side data fetching options. Choose the routing method that best suits your project's needs.

Here are some expanded JavaScript examples to illustrate the differences between App Router and Pages Router in Next.js:

Pages Router Example (with data fetching):

// pages/index.js
import React from 'react';

export async function getStaticProps() {
  // Fetch data from an API or database
  const data = await fetch('https://api.example.com/data').then(res => res.json());

  return {
    props: {
      data,
    },
  };
}

function HomePage({ data }) {
  return (
    <div>
      <h1>Welcome to the home page!</h1>
      <ul>
        {data.map(item => (
          <li key={item.id}>{item.title}</li>
        ))}
      </ul>
    </div>
  );
}

export default HomePage;

App Router Example (with nested layouts and data fetching):

// app/page.js
import React from 'react';

async function getData() {
  const data = await fetch('https://api.example.com/data').then(res => res.json());
  return data;
}

export default async function Home() {
  const data = await getData();

  return (
    <div>
      <h1>Welcome to the home page!</h1>
      <ul>
        {data.map(item => (
          <li key={item.id}>{item.title}</li>
        ))}
      </ul>
    </div>
  );
}

// app/layout.js
export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        <header>My App</header>
        <main>{children}</main>
        <footer>© 2023 My App</footer>
      </body>
    </html>
  );
}

// app/dashboard/page.js
export default function Dashboard() {
  return <h1>User Dashboard</h1>;
}

Explanation:

  • Pages Router: The getStaticProps function fetches data at build time, making it suitable for static content. The HomePage component receives the data as props and renders it.
  • App Router: The getData function fetches data on the server when the page is requested. The Home component uses await to wait for the data before rendering. The RootLayout component provides a consistent layout for all pages within the app directory. The dashboard/page.js demonstrates nested routing within the app directory.

Additional Considerations:

  • Error Handling: Both routers require mechanisms for handling errors during data fetching.
  • Loading States: The App Router can leverage React Suspense for efficient loading states, while the Pages Router may require manual implementation.
  • Client-side Data Fetching: The App Router allows fetching data on the client-side using useEffect or libraries like swr, offering more flexibility but potentially impacting SEO.

Remember to choose the routing method that best aligns with your project's specific requirements and complexity.

Additional Notes

Dynamic Routing:

  • Pages Router: Supports dynamic routing using file names with brackets, like [id].js. This allows creating routes that match patterns and extract parameters.
  • App Router: Also supports dynamic routing using similar syntax with file names like [id].js or [...slug].js. It offers more flexibility for complex routing scenarios.

Nested Routes and Layouts:

  • Pages Router: Nested routes are created by placing files within subdirectories of the pages directory. Layouts can be implemented using components or third-party libraries.
  • App Router: Nested routes and layouts are achieved naturally through the file structure within the app directory. This makes it easier to manage complex application structures.

Data Fetching Strategies:

  • Pages Router:
    • getStaticProps: Fetches data at build time, ideal for static content.
    • getServerSideProps: Fetches data on each request, suitable for dynamic content.
    • getInitialProps: (Legacy) Fetches data on both server and client, but can lead to performance issues.
  • App Router:
    • fetch: Can be used on both server and client for data fetching.
    • swr: A popular library for data fetching and caching, offering features like revalidation and optimistic updates.
    • Server Components: Allow running code only on the server, improving performance and SEO.

Transitioning Between Routers:

  • Next.js allows using both routers in the same project, enabling a gradual migration from Pages Router to App Router.
  • This can be helpful for incrementally adopting the new routing system while maintaining existing functionality.

Community and Resources:

  • The Next.js community is active and provides numerous resources, tutorials, and examples for both routing methods.
  • Official Next.js documentation offers comprehensive guides and API references.

Future of Next.js Routing:

  • The App Router is considered the future direction of routing in Next.js.
  • It is expected to receive continued development and improvements, making it even more powerful and flexible.

Summary

Feature App Router Pages Router
File Structure app directory with nested layouts and components pages directory with files representing routes
Data Fetching Suspense with fetch or libraries like swr (client/server) getServerSideProps or getStaticProps (server-side)
Layouts Built-in support through nested components Manual management using components or libraries
SEO Requires careful consideration Generally better due to server-side rendering
Strengths Flexibility, UI composition control, efficient loading states Simplicity, SEO-friendliness, intuitive file-based routing
Weaknesses SEO considerations, potential client-side rendering implications Less flexibility, manual layout management
Ideal for Complex applications, interactive experiences Simpler projects, content-focused websites, SEO-focused projects

Conclusion

In conclusion, both the App Router and Pages Router in Next.js offer distinct advantages and cater to different project needs. The Pages Router shines in its simplicity and SEO-friendliness, making it ideal for content-focused websites and projects where search engine optimization is paramount. On the other hand, the App Router provides greater flexibility and control over UI composition and data fetching, making it well-suited for complex applications and highly interactive user experiences.

When choosing between the two, carefully consider your project's specific requirements and priorities. For simpler projects or those with a strong emphasis on SEO, the Pages Router remains a reliable choice. However, if you require fine-grained control over your application's structure and data flow, the App Router offers a powerful and adaptable solution.

As Next.js continues to evolve, the App Router is expected to gain further prominence and become the preferred routing method for many developers. Its ability to handle complex routing scenarios, efficient data fetching, and streamlined layout management positions it as a valuable tool for building modern and dynamic web applications.

References

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