Storybook for SvelteKit

Storybook for SvelteKit is a framework that makes it easy to develop and test UI components in isolation for SvelteKit applications.

Install

To install Storybook in an existing SvelteKit project, run this command in your project's root directory:

You can then get started writing stories, running tests and documenting your components. For more control over the installation process, refer to the installation guide.

Requirements

<GetStartedVersions versions={[{ name: 'SvelteKit', range: '≥ 1.0', icon: '/images/logos/renderers/logo-svelte.svg' }, { name: 'Vite', range: '≥ 5', icon: '/images/logos/builders/vite.svg' }]} />

Run Storybook

To run Storybook for a particular project, run the following:

To build Storybook, run:

You will find the output in the configured outputDir (default is storybook-static).

Configure

This section covers SvelteKit support and configuration options.

Supported features

All Svelte language features are supported out of the box, as the Storybook framework uses the Svelte compiler directly. However, SvelteKit has some Kit-specific modules that aren't supported. Here's a breakdown of what will and will not work within Storybook:

How to mock

To mock a SvelteKit import you can define it within parameters.sveltekit_experimental:

The available parameters are documented in the API section, below.

Mocking links

The default link-handling behavior (e.g., when clicking an <a href="..." /> element) is to log an action to the Actions panel.

You can override this by assigning an object to parameters.sveltekit_experimental.hrefs, where the keys are strings representing an href, and the values define your mock. For example:

See the API reference for more information.

Writing native Svelte stories

Storybook provides a Svelte addon maintained by the community, enabling you to write stories for your Svelte components using the template syntax.

Setup

If you initialized your project with the Sveltekit framework, the addon has already been installed and configured for you. However, if you're migrating from a previous version, you'll need to take additional steps to enable this feature.

Run the following command to install the addon.

The CLI's add command automates the addon's installation and setup. To install it manually, see our documentation on how to install addons.

Update your Storybook configuration file (i.e., .storybook/main.js|ts) to enable support for this format.

Configure

By default, the Svelte addon addon offers zero-config support for Storybook's SvelteKit framework. However, you can extend your Storybook configuration file (i.e., .storybook/main.js|ts) and provide additional addon options. Listed below are the available options and examples of how to use them.

Enabling the legacyTemplate option can introduce a performance overhead and should be used cautiously. For more information, refer to the addon's documentation.

Upgrade to Svelte CSF addon v5

With the Svelte 5 release, Storybook's Svelte CSF addon has been updated to support the new features. This guide will help you migrate to the latest version of the addon. Below is an overview of the major changes in version 5.0 and the steps needed to upgrade your project.

Simplified story API

If you are using the Meta component or the meta named export to define the story's metadata (e.g., parameters), you'll need to update your stories to use the new defineMeta function. This function returns an object with the required information, including a Story component that you must use to define your component stories.

{/* prettier-ignore-start */ }

Story templates

If you used the Template component to control how the component renders in the Storybook, this feature was replaced with built-in children support in the Story component, enabling you to compose components and define the UI structure directly in the story.

{/* prettier-ignore-start */ }

If you need support for the Template component, the addon provides a feature flag for backward compatibility. For more information, see the configuration options.

Story slots to snippets

With Svelte's slot deprecation and the introduction of reusable snippets, the addon also introduced support for this feature allowing you to extend the Story component and provide a custom snippet to provide dynamic content to your stories. Story accepts a template snippet, allowing you to create dynamic stories without losing reactivity.

<script>
  import { defineMeta } from '@storybook/addon-svelte-csf';

  import MyComponent from './MyComponent.svelte';

  const { Story } = defineMeta({
    component: MyComponent,
  });
</script>

<Story name="Default" args={{ exampleProperty: true }}>
  {#snippet template(args)}
    <MyComponent {...args}>Reactive component</MyComponent>
  {/snippet}
</Story>

Tags support

If you enabled automatic documentation generation with the autodocs story property, you must replace it with tags. This property allows you to categorize and filter stories based on specific criteria and generate documentation based on the tags applied to the stories.

{/* prettier-ignore-start */ }

FAQ

How do I manually install the SvelteKit framework?

First, install the framework:

Then, update your .storybook/main.js|ts to change the framework property:

Finally, these packages are now either obsolete or part of @storybook/sveltekit, so you no longer need to depend on them directly. You can remove them (npm uninstall, yarn remove, pnpm remove) from your project:

• @storybook/svelte-vite
• storybook-builder-vite
• @storybook/builder-vite

API

Parameters

This framework contributes the following parameters to Storybook, under the sveltekit_experimental namespace:

forms

Type: { enhance: () => void }

Provides mocks for the $app/forms module.

forms.enhance

Type: () => void

A callback that will be called when a form with use:enhance is submitted.

hrefs

Type: Record<[path: string], (to: string, event: MouseEvent) => void | { callback: (to: string, event: MouseEvent) => void, asRegex?: boolean }>

If you have an <a /> tag inside your code with the href attribute that matches one or more of the links defined (treated as regex based if the asRegex property is true) the corresponding callback will be called. If no matching hrefs are defined, an action will be logged to the Actions panel. See Mocking links for an example.

navigation

Type: See SvelteKit docs

Provides mocks for the $app/navigation module.

navigation.goto

Type: See SvelteKit docs

A callback that will be called whenever goto is called. If no function is provided, an action will be logged to the Actions panel.

navigation.pushState

Type: See SvelteKit docs

A callback that will be called whenever pushState is called. If no function is provided, an action will be logged to the Actions panel.

navigation.replaceState

Type: See SvelteKit docs

A callback that will be called whenever replaceState is called. If no function is provided, an action will be logged to the Actions panel.

navigation.invalidate

Type: See SvelteKit docs

A callback that will be called whenever invalidate is called. If no function is provided, an action will be logged to the Actions panel.

navigation.invalidateAll

Type: See SvelteKit docs

A callback that will be called whenever invalidateAll is called. If no function is provided, an action will be logged to the Actions panel.

navigation.afterNavigate

Type: See SvelteKit docs

An object that will be passed to the afterNavigate function, which will be invoked when the onMount event fires.

stores

Type: See SvelteKit docs

Provides mocks for the $app/stores module.

stores.navigating

Type: See SvelteKit docs

A partial version of the navigating store.

stores.page

Type: See SvelteKit docs

A partial version of the page store.

stores.updated

Type: boolean

A boolean representing the value of updated (you can also access updated.check() which will be a no-op).

state

Type: See SvelteKit docs

Provides mocks for the $app/state module.

state.navigating

Type: See SvelteKit docs

A partial version of the navigating store.

state.page

Type: See SvelteKit docs

A partial version of the page store.

state.updated

Type: { current: boolean }

An object representing the current value of updated. You can also access updated.check(), which will be a no-op.

Options

You can pass an options object for additional configuration if needed:

{/* prettier-ignore-start */ }

The available options are:

builder

Type: Record<string, any>

Configure options for the framework's builder. For Sveltekit, available options can be found in the Vite builder docs.

docgen

Type: boolean

Default: true

Enables or disables automatic documentation generation for component properties. When disabled, Storybook will skip the docgen processing step during build, which can improve build performance.

When to disable docgen

Disabling docgen can improve build performance for large projects, but argTypes won't be inferred automatically, which will prevent features like Controls and docs from working as expected. To use those features, you will need to define argTypes manually.