In this chapter, we will learn how to implement layouts in a Next.js 13 application using the Page Router. Although Next.js 13's App Router introduced a native system for working with layouts, the Page Router also allows for creating reusable layouts using custom components.

Layouts enable creating a consistent structure across the application, including common elements like headers, footers, or navigation bars, without having to repeat code on each page.

Creating Layouts in the Page Router

In the Page Router, layouts do not have native support like in the App Router, but we can manually organize them as reusable components. Next, we'll see how to create a basic layout that applies to several pages of our application.

Basic Layout

Let's create a basic layout that includes a header and a footer. This layout will wrap the content of our pages.

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The layout Layout.js can be used on various pages to maintain UI consistency.

Applying the Layout to a Page

Once we have created the layout, we can apply it to pages by importing and wrapping the content of each page within the Layout component.

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This pattern allows reusing the layout across multiple pages without duplicating code.

Nested Layouts

In some applications, it can be useful to have nested layouts, where certain UI components are shared between different routes, but other components vary. To implement nested layouts in the Page Router, we can combine multiple layout components.

Example of Nested Layout

Let's assume we have a general layout for the entire application, but we want a specific layout for the admin section (/admin).

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In this example, we reuse the general layout for the entire application, but add a specific layout with a side navigation bar for the admin section.

Advantages of Using Layouts in the Page Router

Although the Page Router does not have native support for layouts like the App Router, implementing custom layouts has several advantages:

1. Code Reuse: Layouts allow keeping common components, like headers and footers, in one place.

2. UI Consistency: Applying a global layout to all pages ensures the application has a consistent appearance.

3. Flexibility: Nested layouts allow adapting different sections of the application with their own specific components.

Layout Optimization

To improve application performance when using layouts, we can apply techniques like dynamic loading of components that are not critical for the initial render.

Example of Dynamic Loading

We can use Next.js's dynamic() function to load components dynamically. This is useful for parts of the layout that are not essential at the moment of the first render.

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This can help to reduce the initial load time, especially if the footer or any other part of the layout contains content that is not critical.

Conclusion

In this chapter, we have learned how to implement reusable and nested layouts in a Next.js 13 application using the Page Router. Layouts allow us to maintain UI consistency and reduce code duplication. Although the Page Router does not have native support for layouts like the App Router, we can create custom layouts that fit the needs of our application.