`<head>`

The <head> tags (e.g. <title> or <meta name="description">) are defined by our server-side render() hook.

We can also define <head> tags on a page-by-page basis and on a component-by-component basis, see sections below.

// /renderer/_default.page.server.js
// Environment: server

import { escapeInject, dangerouslySkipEscape } from 'vite-plugin-ssr/server'
import { renderToHtml } from 'some-ui-framework'

export { render }

async function render(pageContext) {
  return escapeInject`<html>
    <head>
      <title>SpaceX</title>
      <meta name="description" content="We deliver payload to space.">
    </head>
    <body>
      <div id="root">
        ${dangerouslySkipEscape(await renderToHtml(pageContext.Page))}
      </div>
    </body>
  </html>`
}

By page (static)

To define <head> tags for a specific page, we can use a Custom Export.

// /pages/about.page.js

// Custom Export
export const documentProps = {
  // This title and description will override the defaults
  title: 'About SpaceX',
  description: 'Our mission is to explore the galaxy.'
}

// /renderer/_default.page.server.js
// Environment: server

import { escapeInject, dangerouslySkipEscape } from 'vite-plugin-ssr/server'
import { renderToHtml } from 'some-ui-framework'

export { render }

async function render(pageContext) {
  // Our custom export is available here as `pageContext.exports.documentProps`
  const { documentProps } = pageContext.exports

  // Defaults
  const title = documentProps.title || 'SpaceX'
  const description = documentProps.description || 'We deliver payload to space.'

  return escapeInject`<html>
    <head>
      <title>${title}</title>
      <meta name="description" content="${description}">
    </head>
    <body>
      <div id="root">
        ${dangerouslySkipEscape(await renderToHtml(pageContext.Page))}
      </div>
    </body>
  </html>`
}

By page (dynamic)

To define <head> tags that are dynamic (determined at run-time), we can also use a Custom Export.

// /pages/rocket.page.route.js
export const '/rocket/@rocketSlug'

// /pages/rocket.page.js

// Custom Export
export { getDocumentProps }

// getDocumentProps() can use fetched data to provide <title> and <meta name="description">
function getDocumentProps(pageProps) {
  return {
    title: pageProps.product.name,
    description: pageProps.product.description
  }
}

// /renderer/_default.page.server.js
// Environment: server

export { render }

import { escapeInject, dangerouslySkipEscape } from 'vite-plugin-ssr/server'
import { renderToHtml } from 'some-ui-framework'

async function render(pageContext) {
  // `pageProps` is provided by our data fetching mechanism, see the "Data Fetching" Guide.
  const { Page, pageProps } = pageContext

  // Custom exports are available at pageContext.exports
  const { getDocumentProps } = pageContext.exports

  const title = (
    // Conditional call in case a page doesn't define getDocumentProps()
    getDocumentProps?.(pageProps).title ||
    // Default for pages that don't define getDocumentProps()
    'SpaceX'
  )
  const description = (
    // Conditional call in case a page doesn't define getDocumentProps()
    getDocumentProps?.(pageProps).description ||
    // Default for pages that don't define getDocumentProps()
    'We deliver payload to space.'
  )

  return escapeInject`<html>
    <head>
      <title>${title}</title>
      <meta name="description" content="${description}">
    </head>
    <body>
      <div id="root">
        ${dangerouslySkipEscape(await renderToHtml(pageContext.Page))}
      </div>
    </body>
  </html>`
}

By component

To define <head> tags by some deeply nested view (React/Vue/...) component:

We add documentProps to passToClient.
We pass pageContext.documentProps to all components, see Guides > Access pageContext anywhere.
We modify pageContext.documentProps in the deeply nested component.

For example:

// /renderer/_default.page.server.js
// Environment: server

import { escapeInject, dangerouslySkipEscape } from 'vite-plugin-ssr/server'
import renderToHtml from 'some-ui-framework'

export async function render(pageContext) {
  // We use our UI framework to pass `pageContext.documentProps` to all components
  // of our component tree. (E.g. React Context or Vue's `app.config.globalProperties`.)
  const pageHtml = await renderToHtml(
    <ContextProvider documentProps={pageContext.documentProps} >
      <Page />
    </ContextProvider>
  )

  // What happens here is:
  // 1. Our UI framework passed `documentProps` to all our components
  // 2. One of our (deeply nested) component modified `documentProps`
  // 3. We now render `documentProps` to HTML meta tags
  return escapeInject`<html>
    <head>
      <title>${pageContext.documentProps.title}</title>
      <meta name="description" content="${pageContext.documentProps.description}">
    </head>
    <body>
      <div id="app">
        ${dangerouslySkipEscape(pageHtml)}
      </div>
    </body>
  </html>`
}

// Somewhere in a component deep inside our component tree

// Thanks to our previous steps, `documentProps` is available here.
documentProps.title = 'I was set by some deep component.'
documentProps.description = 'Me too.'

Client Routing

If we use Client Routing, we need to make sure to update document.title upon page navigation:

// /renderer/_default.page.server.js
// Environment: server

// We make `pageContext.documentProps` available in the browser.
export const passToClient = ['documentProps', 'pageProps']

// /renderer/_default.page.client.js
// Environment: browser

export { render }

function render(pageContext) {
  if (!pageContext.isHydration) {
    // Page navigation — we update the website's title
    document.title = pageContext.documentProps.title
  }
  // ...
}

Libraries

We can also use libraries such as @vueuse/head or react-helmet.

We recommend to use such library only if you have a rationale: the aforementioned solutions are simpler and work for most use cases.

Head libraries already sanitize the HTML <head>, this means we can skip escapeInject and wrap the overall result with dangerouslySkipEscape().

// /renderer/_default.page.server.js
// Environment: server

import { dangerouslySkipEscape } from 'vite-plugin-ssr/server'
import { renderToHtml } from 'some-ui-framework'

export async function render(pageContext) {
  return dangerouslySkipEscape(await renderToHtml(pageContext.Page))
}

Markdown

For pages defined with markdown, see Integration > Markdown > <head> (pageContext.exports).

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