{"pageProps":{"routes":[{"title":"Documentation","heading":true,"routes":[{"title":"Getting Started","path":"/docs/getting-started.md"},{"title":"Basic Features","open":true,"routes":[{"title":"Pages","path":"/docs/basic-features/pages.md"},{"title":"Data fetching","path":"/docs/basic-features/data-fetching.md"},{"title":"Built-in CSS Support","path":"/docs/basic-features/built-in-css-support.md"},{"title":"Static File Serving","path":"/docs/basic-features/static-file-serving.md"},{"title":"TypeScript","path":"/docs/basic-features/typescript.md"},{"title":"Environment Variables","path":"/docs/basic-features/environment-variables.md"}]},{"title":"Routing","routes":[{"title":"Introduction","path":"/docs/routing/introduction.md"},{"title":"Dynamic Routes","path":"/docs/routing/dynamic-routes.md"},{"title":"Imperatively","path":"/docs/routing/imperatively.md"},{"title":"Shallow Routing","path":"/docs/routing/shallow-routing.md"}]},{"title":"API Routes","routes":[{"title":"Introduction","path":"/docs/api-routes/introduction.md"},{"title":"Dynamic API Routes","path":"/docs/api-routes/dynamic-api-routes.md"},{"title":"API Middlewares","path":"/docs/api-routes/api-middlewares.md"},{"title":"Response Helpers","path":"/docs/api-routes/response-helpers.md"}]},{"title":"Deployment","path":"/docs/deployment.md"},{"title":"Advanced Features","routes":[{"title":"Preview Mode","path":"/docs/advanced-features/preview-mode.md"},{"title":"Dynamic Import","path":"/docs/advanced-features/dynamic-import.md"},{"title":"Automatic Static Optimization","path":"/docs/advanced-features/automatic-static-optimization.md"},{"title":"Static HTML Export","path":"/docs/advanced-features/static-html-export.md"},{"title":"Absolute Imports and Module Path Aliases","path":"/docs/advanced-features/module-path-aliases.md"},{"title":"AMP Support","routes":[{"title":"Introduction","path":"/docs/advanced-features/amp-support/introduction.md"},{"title":"Adding AMP Components","path":"/docs/advanced-features/amp-support/adding-amp-components.md"},{"title":"AMP Validation","path":"/docs/advanced-features/amp-support/amp-validation.md"},{"title":"AMP in Static HTML export","path":"/docs/advanced-features/amp-support/amp-in-static-html-export.md"},{"title":"TypeScript","path":"/docs/advanced-features/amp-support/typescript.md"}]},{"title":"Customizing Babel Config","path":"/docs/advanced-features/customizing-babel-config.md"},{"title":"Customizing PostCSS Config","path":"/docs/advanced-features/customizing-postcss-config.md"},{"title":"Custom Server","path":"/docs/advanced-features/custom-server.md"},{"title":"Custom `App`","path":"/docs/advanced-features/custom-app.md"},{"title":"Custom `Document`","path":"/docs/advanced-features/custom-document.md"},{"title":"Custom Error Page","path":"/docs/advanced-features/custom-error-page.md"},{"title":"`src` Directory","path":"/docs/advanced-features/src-directory.md"},{"title":"Multi Zones","path":"/docs/advanced-features/multi-zones.md"},{"title":"Measuring performance","path":"/docs/advanced-features/measuring-performance.md"}]},{"title":"Upgrade Guide","path":"/docs/upgrading.md"},{"title":"FAQ","path":"/docs/faq.md"}]},{"title":"API Reference","heading":true,"routes":[{"title":"CLI","path":"/docs/api-reference/cli.md"},{"title":"next/router","path":"/docs/api-reference/next/router.md"},{"title":"next/link","path":"/docs/api-reference/next/link.md"},{"title":"next/head","path":"/docs/api-reference/next/head.md"},{"title":"next/amp","path":"/docs/api-reference/next/amp.md"},{"title":"Data Fetching","routes":[{"title":"getInitialProps","path":"/docs/api-reference/data-fetching/getInitialProps.md"}]},{"title":"next.config.js","routes":[{"title":"Introduction","path":"/docs/api-reference/next.config.js/introduction.md"},{"title":"Environment Variables","path":"/docs/api-reference/next.config.js/environment-variables.md"},{"title":"Custom Page Extensions","path":"/docs/api-reference/next.config.js/custom-page-extensions.md"},{"title":"CDN Support with Asset Prefix","path":"/docs/api-reference/next.config.js/cdn-support-with-asset-prefix.md"},{"title":"Build Target","path":"/docs/api-reference/next.config.js/build-target.md"},{"title":"Custom Webpack Config","path":"/docs/api-reference/next.config.js/custom-webpack-config.md"},{"title":"Compression","path":"/docs/api-reference/next.config.js/compression.md"},{"title":"Static Optimization Indicator","path":"/docs/api-reference/next.config.js/static-optimization-indicator.md"},{"title":"Runtime Configuration","path":"/docs/api-reference/next.config.js/runtime-configuration.md"},{"title":"Disabling x-powered-by","path":"/docs/api-reference/next.config.js/disabling-x-powered-by.md"},{"title":"Disabling ETag Generation","path":"/docs/api-reference/next.config.js/disabling-etag-generation.md"},{"title":"Setting a custom build directory","path":"/docs/api-reference/next.config.js/setting-a-custom-build-directory.md"},{"title":"Configuring the Build ID","path":"/docs/api-reference/next.config.js/configuring-the-build-id.md"},{"title":"Configuring onDemandEntries","path":"/docs/api-reference/next.config.js/configuring-onDemandEntries.md"},{"title":"Ignoring TypeScript Errors","path":"/docs/api-reference/next.config.js/ignoring-typescript-errors.md"},{"title":"exportPathMap","path":"/docs/api-reference/next.config.js/exportPathMap.md"}]}]}],"data":{"description":"Extend the default document markup added by Next.js."},"route":{"title":"Custom `Document`","path":"/docs/advanced-features/custom-document.md"},"html":"

Custom Document

\n

A custom Document is commonly used to augment your application's <html> and <body> tags. This is necessary because Next.js pages skip the definition of the surrounding document's markup.

\n

A custom Document can also include getInitialProps for expressing asynchronous server-rendering data requirements.

\n

To override the default Document, create the file ./pages/_document.js and extend the Document class as shown below:

\n
import Document, { Html, Head, Main, NextScript } from 'next/document'\n\nclass MyDocument extends Document {\n  static async getInitialProps(ctx) {\n    const initialProps = await Document.getInitialProps(ctx)\n    return { ...initialProps }\n  }\n\n  render() {\n    return (\n      <Html>\n        <Head />\n        <body>\n          <Main />\n          <NextScript />\n        </body>\n      </Html>\n    )\n  }\n}\n\nexport default MyDocument\n
\n

<Html>, <Head />, <Main /> and <NextScript /> are required for the page to be properly rendered.

\n

Custom attributes are allowed as props, like lang:

\n
<Html lang=\"en\">\n
\n

The ctx object is equivalent to the one received in getInitialProps, with one addition:

\n\n

Caveats\n \n \n \n \n

\n\n

Customizing renderPage\n \n \n \n \n

\n
\n

It should be noted that the only reason you should be customizing renderPage is for usage with css-in-js libraries that need to wrap the application to properly work with server-side rendering.

\n
\n

It takes as argument an options object for further customization:

\n
import Document from 'next/document'\n\nclass MyDocument extends Document {\n  static async getInitialProps(ctx) {\n    const originalRenderPage = ctx.renderPage\n\n    ctx.renderPage = () =>\n      originalRenderPage({\n        // useful for wrapping the whole react tree\n        enhanceApp: App => App,\n        // useful for wrapping in a per-page basis\n        enhanceComponent: Component => Component,\n      })\n\n    // Run the parent `getInitialProps`, it now includes the custom `renderPage`\n    const initialProps = await Document.getInitialProps(ctx)\n\n    return initialProps\n  }\n}\n\nexport default MyDocument\n
"},"__N_SSG":true}