prerender()
hookSee Guides > Pre-rendering (SSG) for an overview of how to pre-render your app.
Most of the time, we use the prerender()
hook in order to provide the URLs of parameterized routes.
// /pages/movie.page.route.js
// Environment: Node.js
export default '/movie/@movieId'
// /pages/movie.page.server.js
// Environment: Node.js
export { prerender }
async function prerender() {
const movies = await Movie.findAll()
const moviePageURLs = movies.map(movie => '/movie/' + movie.id)
return moviePageURLs
}
If we don't have any parameterized route, then we can pre-render our app without defining any
prerender()
hook.
The
prerender()
hooks are called when we run$ vite build
. (Theprerender()
hooks are never called in development.)
pageContext
If we have a high number of pages that are to be pre-rendered, then running the command $ vite build
may become slow.
We can make it significantly faster by providing the pageContext
of pages in prerender()
hooks.
// /pages/movie.page.route.js
// Environment: Node.js
export default '/movie/@movieId'
// /pages/movie.page.server.js
// Environment: Node.js
export { prerender }
async function prerender() {
const movies = await Movie.findAll()
const moviePages = (
movies
.map(movie => {
const url = '/movie/' + movie.id
const pageProps = { movie }
const pageContext = { pageProps }
return {
url,
// Because we already provide the `pageContext`, vite-plugin-ssr will *not* call
// the `onBeforeRender()` hook for `url`.
pageContext
}
/* We could also only return `url` and not provide `pageContext`. In that case
* vite-plugin-ssr would call the `onBeforeRender()` hook. But that would be wasteful
* since we already have all the data of all movies from our `await Movie.findAll()` call.
* Instead, we provide `pageContext` to make the pre-rendering build step faster.
*/
// return { url }
})
)
// We can also return URLs that don't match the page's route.
// That way we can provide the `pageContext` of other pages.
// Here we provide the `pageContext` of the `/movies` page since
// we already have the data.
const movieListPage = {
url: '/movies', // Note how the URL `/movies` isn't part of the page's route `/movie/@movieId`
pageContext: {
pageProps: {
// We filter out the data we don't need in order to minimize what is sent to the browser.
// We explain this practice at https://vite-plugin-ssr.com/data-fetching
movieList: movies.map(({id, title}) => ({id, title})
}
}
}
return [movieListPage, ...moviePages]
}
Essentially, the prerender()
hook allows us to prefetch data for multiple pages at once.
Providing
pageContext
inprerender()
hooks should only be used for making the pre-rendering build step faster and we recommend against usingprerender()
hooks for other purposes.For example, we should avoid providing additional
pageContext
inprerender()
hooks that wouldn't otherwise exist. Instead, we should make sure that ouronBeforeRender()
hooks provide all thepageContext
we need.The reason being that
prerender()
hooks are never called in development and we should keep our app consistent between development and production.
React Example:
build:prerender
script)prerender()
hook)prerender()
hook)Vue Example:
build:prerender
script)prerender()
hook)prerender()
hook)