next js custom document with code examples 2

Next.js is a powerful framework for building server-rendered React applications. One of the features it offers is the ability to customize the document that is sent to the browser when a page is requested. This allows you to add custom meta tags, scripts, and styles to the head of the document, as well as control the contents of the body.

To create a custom document, you need to create a new file in your Next.js project's pages directory called _document.js. This file should export a React component that extends the Document component provided by Next.js. Here is an example of a basic custom document:

import Document, { Html, Head, Main, NextScript } from 'next/document'

class MyDocument extends Document {
  static async getInitialProps(ctx) {
    const initialProps = await Document.getInitialProps(ctx)
    return { ...initialProps }
  }

  render() {
    return (
      <Html>
        <Head>
          <title>My custom document</title>
        </Head>
        <body>
          <Main />
          <NextScript />
        </body>
      </Html>
    )
  }
}

export default MyDocument

In this example, we are importing the Document, Html, Head, Main, and NextScript components from next/document. We then create a new class called MyDocument that extends Document. The getInitialProps method is used to retrieve any props that need to be passed to the document. In this case, we are calling the getInitialProps method of the base Document class and spreading its return value into our own props.

In the render method, we return the JSX that will be rendered as the document. The Html component is used as the root element and contains the Head and body components. The Head component is used to add custom meta tags, scripts, and styles to the head of the document, and the Main component is used to render the main content of the page. The NextScript component is used to render the script that is needed for Next.js to work properly.

You can add custom meta tags, scripts, and styles to the head of the document by adding them to the Head component. For example, to add a custom meta tag, you can use the following code:

<Head>
  <title>My custom document</title>
  <meta name="description" content="This is my custom document" />
</Head>

You can also add custom styles and scripts to the head of the document. For example, to add a custom stylesheet, you can use the following code:

<Head>
  <title>My custom document</title>
  <link rel="stylesheet" href="/styles.css" />
</Head>

And to add custom script, you can use the following code:

<Head>
  <title>My custom document</title>
  <script src="/custom-script.js"></script>
</Head>

It is also possible to add custom elements to the body of the document. To do this, you can simply add them as children of the body element in your render method.
One powerful feature of Next.js is its ability to server-render your React application. This means that the initial HTML that is sent to the browser contains the fully rendered content of the page, which can improve the perceived load time for your users. However, in order to take full advantage of server-rendering, it is important to understand how to properly handle asynchronous data loading in your application.

One way to handle asynchronous data loading in Next.js is to use the getInitialProps method in your custom document. This method is called on the server before the page is rendered, and it allows you to asynchronously fetch data that is needed for the page. You can then pass this data as props to the page, which will be available on the client as well. Here is an example of how you might use the getInitialProps method to fetch data from an API:

import Document, { Html, Head, Main, NextScript } from 'next/document'
import axios from 'axios'

class MyDocument extends Document {
  static async getInitialProps(ctx) {
    const initialProps = await Document.getInitialProps(ctx)

    // Fetch data from an API
    const data = await axios.get('https://my-api.com/data')

    // Pass the data as props
    return { ...initialProps, data }
  }

  render() {
    // Render the page using the data
    return (
      <Html>
        <Head>
          <title>My custom document</title>
        </Head>
        <body>
          <Main />
          <NextScript />
        </body>
      </Html>
    )
  }
}

export default MyDocument

Another feature that can be added to Next.js application is dynamic routing, which allows you to define routes that can accept variables. For example, you might have a route that displays information about a specific product, and the product ID is part of the URL. To define dynamic routes in Next.js, you need to create a new directory called pages in your project's root directory and then create a new file for each route. The name of the file determines the path of the route. For example, if you create a file called [id].js, the route will be /:id.

Here is an example of how you might define a dynamic route in Next.js:

import { useRouter } from 'next/router'

const Product = () => {
  const router = useRouter()
  const { id } = router.query

  return (
    <div>
      <h1>Product {id}</h1>
    </div>
  )
}

export default Product

The useRouter hook can be used to access the router object, which contains information about the current route, including the query params. In this example, we are destructuring the id from the query object and using it to display the product ID on the page.

In addition, Next.js also supports Static Site Generation (SSG) which allows you to pre-render your pages at build time. This can be useful if your data is not changing frequently and you want to improve the performance of your site. It works by calling the getStaticProps method instead of getInitialProps in your pages. The

next js custom document with code examples 2

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