Build and deploy

Static site generation

To use SvelteKit as a static site generator (SSG), use adapter-static.

This will prerender your entire site as a collection of static files. If you'd like to prerender only some pages and dynamically server-render others, you will need to use a different adapter together with the prerender option.

Usagepermalink

Install with npm i -D @sveltejs/adapter-static, then add the adapter to your svelte.config.js:

svelte.config.js

ts
import adapter from '@sveltejs/adapter-static';
Cannot find module '@sveltejs/adapter-static' or its corresponding type declarations.2307Cannot find module '@sveltejs/adapter-static' or its corresponding type declarations. 
export default {
  kit: {
    adapter: adapter({
      // default options are shown. On some platforms
      // these options are set automatically — see below
      pages: 'build',
      assets: 'build',
      fallback: undefined,
      precompress: false,
      strict: true
    })
  }
};

...and add the prerender option to your root layout:

src/routes/+layout.js

ts
// This can be false if you're using a fallback (i.e. SPA mode)
export const prerender = true;

src/routes/+layout.ts

ts
// This can be false if you're using a fallback (i.e. SPA mode)
export const prerender = true;

You must ensure SvelteKit's trailingSlash option is set appropriately for your environment. If your host does not render /a.html upon receiving a request for /a then you will need to set trailingSlash: 'always' in your root layout to create /a/index.html instead.

Zero-config supportpermalink

Some platforms have zero-config support (more to come in future):

Vercel

On these platforms, you should omit the adapter options so that adapter-static can provide the optimal configuration:

svelte.config.js

export default {
  kit: {
		adapter: adapter({...})
		adapter: adapter()
  }
};

Optionspermalink

pagespermalink

The directory to write prerendered pages to. It defaults to build.

assetspermalink

The directory to write static assets (the contents of static, plus client-side JS and CSS generated by SvelteKit) to. Ordinarily this should be the same as pages, and it will default to whatever the value of pages is, but in rare circumstances you might need to output pages and assets to separate locations.

fallbackpermalink

Specify a fallback page for SPA mode, e.g. index.html or 200.html or 404.html.

precompresspermalink

If true, precompresses files with brotli and gzip. This will generate .br and .gz files.

strictpermalink

By default, adapter-static checks that either all pages and endpoints (if any) of your app were prerendered, or you have the fallback option set. This check exists to prevent you from accidentally publishing an app where some parts of it are not accessible, because they are not contained in the final output. If you know this is ok (for example when a certain page only exists conditionally), you can set strict to false to turn off this check.

GitHub Pagespermalink

When building for GitHub Pages, if your repo name is not equivalent to your-username.github.io, make sure to update config.kit.paths.base to match your repo name. This is because the site will be served from https://your-username.github.io/your-repo-name rather than from the root.

You'll also want to generate a fallback 404.html page to replace the default 404 page shown by GitHub Pages.

A config for GitHub Pages might look like the following:

svelte.config.js

ts
import adapter from '@sveltejs/adapter-static';
Cannot find module '@sveltejs/adapter-static' or its corresponding type declarations.2307Cannot find module '@sveltejs/adapter-static' or its corresponding type declarations.
/** @type {import('@sveltejs/kit').Config} */
const config = {
	kit: {
		adapter: adapter({
			fallback: '404.html'
		}),
		paths: {
			base: process.argv.includes('dev') ? '' : process.env.BASE_PATH
Type 'string | undefined' is not assignable to type '"" | `/${string}` | undefined'.
  Type 'string' is not assignable to type '"" | `/${string}` | undefined'.2322Type 'string | undefined' is not assignable to type '"" | `/${string}` | undefined'.
  Type 'string' is not assignable to type '"" | `/${string}` | undefined'.		}
	}
};

export default config;

You can use GitHub actions to automatically deploy your site to GitHub Pages when you make a change. Here's an example workflow:

.github/workflows/deploy.yml

yaml
name: Deploy to GitHub Pages

on:
  push:
    branches: 'main'

jobs:
  build_site:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3

      # If you're using pnpm, add this step then change the commands and cache key below to use `pnpm`
      # - name: Install pnpm
      #   uses: pnpm/action-setup@v2
      #   with:
      #     version: 8

      - name: Install Node.js
        uses: actions/setup-node@v3
        with:
          node-version: 18
          cache: npm

      - name: Install dependencies
        run: npm install

      - name: build
        env:
          BASE_PATH: '/${{ github.event.repository.name }}'
        run: |
          npm run build

      - name: Upload Artifacts
        uses: actions/upload-pages-artifact@v2
        with:
          # this should match the `pages` option in your adapter-static options
          path: 'build/'

  deploy:
    needs: build_site
    runs-on: ubuntu-latest

    permissions:
      pages: write
      id-token: write

    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}

    steps:
      - name: Deploy
        id: deployment
        uses: actions/deploy-pages@v2

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