Next.js Layouts Explained

When building a Next.js application, you’ll likely find yourself creating shared components and templates that are used across multiple pages. One of the most powerful tools for achieving this is the use of Next.js layouts.

What are layouts?

Layouts are higher-order components that wrap your page components in shared UI elements like headers, footers, and navigation menus. They’re a way to extract common UI elements and stateful logic so that they can be reused across multiple pages.

With layouts, you can define the basic structure of your application once and reuse it across all of your pages. This can be particularly useful when you want to maintain a consistent user experience or when you have complex UI elements that need to be shared across multiple pages.

The benefits of layouts

There are several benefits to using layouts in your Next.js application:

• Consistency: With layouts, you can ensure that your application has a consistent look and feel across all of your pages. This can help to improve the user experience and make your application feel more professional.

• Reusability: By extracting common UI elements and stateful logic into layouts, you can reuse them across multiple pages. This can help to reduce code duplication and make your application easier to maintain.

• Maintainability: By separating the concerns of layout and content, you can make your code more modular and easier to reason about. This can make it easier to make changes to your application in the future.

• Performance: By sharing components across multiple pages, you can reduce the amount of code that needs to be downloaded by the browser. This can help to improve the performance of your application.

• Shared state: By using layouts, you can share state between pages. This can be useful for things like maintaining a user’s session or storing data that needs to be shared across multiple pages. The state be shared between all pages that are wrapped by the same layout.

How to use layouts

To use a layout in your Next.js application, you’ll need to create a layout component that wraps your page components. Here’s an example of a simple layout component:

import Header from './Header';
import Footer from './Footer';

const Layout = ({ children }) => (
  <>
    <Header />
    <main>{children}</main>
    <Footer />
  </>
);
export default Layout;

In this example, we’re creating a layout component that includes a header and a footer. We’re also using the children prop to render the content of our page.

To use this layout, we’ll need to modify our _app.tsx file. Here’s an example of what the modified _app.tsx file might look like:

import type { AppProps } from 'next/app';
import Layout from '../components/Layout';

function MyApp({ Component, pageProps }: AppProps) {
  const getLayout = Component.getLayout || ((page) => <Layout>{page}</Layout>);
  return getLayout(<Component {...pageProps} />);
}

export default MyApp;

In this example, we’re creating a custom MyApp component that wraps all of our page components in our Layout component. We’re also defining a getLayout function that can be used by individual pages to define their own layouts.

Using TypeScript with layouts If you’re using TypeScript with Next.js, you may want to create a custom type for your layouts. Here’s an example of how you might do that:

import type { NextPage } from 'next';
import type { ReactElement, ReactNode } from 'react';

export type NextPageWithLayout<P = {}, IP = P> = NextPage<P, IP> & {
  getLayout?: (page: ReactElement) => ReactNode;
};
  

In this example, we’re creating a new type called NextPageWithLayout that extends the NextPage type from Next.js. We

Now that we’ve defined our types and interfaces, let’s implement them in our _app.tsx file. First, we need to import our new types and interfaces:

import type { AppProps } from 'next/app'
import type { NextPageWithLayout } from '../types/NextPageWithLayout'

Next, we need to update our App component to include the layout functionality. We can do this by updating the Component prop to be of type NextPageWithLayout and then calling the getLayout function with the Component and pageProps.children as its arguments:

function MyApp({ Component, pageProps }: AppPropsWithLayout) {
  const getLayout = Component.getLayout ?? ((page) => page)
  return <>{getLayout(<Component {...pageProps} />)}</>
}
export default MyApp

Here, we’re checking if the Component has a getLayout function defined. If it does, we use it to wrap the Component and pass in pageProps.children as the content of the layout. If it doesn’t, we simply render the Component without a layout.

With this setup, we can now easily define layouts for our pages by defining a getLayout function in each page’s module file:

import type { NextPage } from 'next'
import type { NextPageWithLayout } from '../types/NextPageWithLayout'
import Layout from '../components/Layout'

type Props = {
  title: string
}

const Page: NextPageWithLayout<Props> = ({ title }) => {
  return (
    <>
      <h1>{title}</h1>
      <p>This is a page with a layout.</p>
    </>
  )
}

Page.getLayout = function getLayout(page) {
  return <Layout>{page}</Layout>
}

export default Page

Here, we’re defining a Page component that uses the NextPageWithLayout type we defined earlier. We’re also defining a getLayout function on the component that returns the Layout component with the page content as its children.

With this setup, we can easily define layouts for all of our pages and ensure that they are all typed correctly using TypeScript. Additionally, we get the benefits of layouts like shared state and preserved state after page navigation.

Conclusion

In conclusion, as a developer, I believe that Next.js layouts offer a simple and efficient way to structure your application’s layout and manage state in a centralized and scalable manner. They provide a way to abstract away the complexity of managing shared components and state across pages, while also offering a clean and organized codebase. By using Next.js layouts, I have found that I can save time and resources while also improving the overall user experience.

I hope this article has helped you understand the benefits of using Next.js layouts and how to implement them in your projects. Remember, layouts are not a requirement, but they can greatly improve the structure and maintainability of your code. Happy coding!