Component Story Format (CSF)

CSF Next is the next evolution of Storybook's Component Story Format (CSF). This new API uses a pattern called factory functions to provide full type safety to your Storybook stories, making it easier to configure addons correctly and unlocking the full potential of Storybook's features.

This reference provides an overview of the API and a migration guide to upgrade from prior CSF versions.

Overview

The CSF Next API is composed of functions to help you write stories. Note how three of the functions operate as factories, each producing the next function in the chain (definePreview → preview.meta → meta.story), providing full type safety at each step.

defineMain

With CSF Next, your main Storybook config is specified by the defineMain function. This function is type-safe and will automatically infer types for your project.

// Replace your-framework with the framework you are using (e.g., react-vite, nextjs, nextjs-vite)
import { defineMain } from '@storybook/your-framework/node';
 
export default defineMain({
  framework: '@storybook/your-framework',
  stories: ['../src/**/*.mdx', '../src/**/*.stories.@(js|jsx|mjs|ts|tsx)'],
  addons: ['@storybook/addon-a11y'],
});

definePreview

Similarly, the definePreview function specifies your project's story configuration. This function is also type-safe and will infer types throughout your project.

Importantly, by specifying addons here, their types will be available throughout your project, enabling autocompletion and type checking.

You will import the result of this function, preview, in your story files to define the component meta.

// Replace your-framework with the framework you are using (e.g., react-vite, nextjs, nextjs-vite)
import { definePreview } from '@storybook/your-framework';
import addonA11y from '@storybook/addon-a11y';
 
export default definePreview({
  // 👇 Add your addons here
  addons: [addonA11y()],
  parameters: {
    // type-safe!
    a11y: {
      options: { xpath: true },
    },
  },
});

preview.meta

The meta function on the preview object is used to define the metadata for your stories. It accepts an object containing the component, title, parameters, and other story properties.

import preview from '../.storybook/preview';
 
import { Button } from './Button';
 
const meta = preview.meta({
  component: Button,
  parameters: {
    // type-safe!
    layout: 'centered',
  }
});

// ✅ Absolute imports won't break if you move story files around
import preview from '#.storybook/preview';
 
// ❌ Relative imports can break if you move story files around
import preview from '../../../.storybook/preview';

{
  "imports": {
    "#*": ["./*", "./*.ts", "./*.tsx"],
  },
}

meta.story

Finally, the story function on the meta object defines the stories. This function accepts an object containing the name, args, parameters, and other story properties.

// ...from above
const meta = preview.meta({ /* ... */ });
 
export const Primary = meta.story({
  args: {
    primary: true,
  },
});

<Story>.extend

You can use the .extend method to create a new story based on an existing one, with the option to override or add new properties.

// ...from above
const meta = preview.meta({ /* ... */ });
 
export const Example = meta.story({
  args: {
    primary: true,
    exampleArray: ['a', 'b'],
    exampleObject: { a: 'a', b: 'b' },
  },
  parameters: {
    exampleArray: ['a', 'b'],
    exampleObject: { a: 'a', b: 'b' },
  },
  tags: ['a'],
});
 
/* 
 * 👇 Final values applied:
 *    {
 *      args: {
 *        primary: true,
 *        disabled: true,
 *        exampleArray: ['c'],
 *        exampleObject: { a: 'c' }
 *      },
 *      parameters: {
 *        exampleArray: ['c'],
 *        exampleObject: { a: 'c', b: 'b' }
 *      },
 *      tags: ['a', 'b']
 *    }
 */
export const ExtendedExample = Example.extend({
  args: {
    disabled: true,
    exampleArray: ['c'],
    exampleObject: { a: 'c' },
  },
  parameters: {
    disabled: true,
    exampleArray: ['c'],
    exampleObject: { a: 'c' },
  },
  tags: ['b'],
});

// ...from above
const meta = preview.meta({ /* ... */ });
 
export const Primary = meta.story({
  args: {
    primary: true,
  },
});
 
export const PrimaryDisabled = Primary.extend({
  args: {
    disabled: true,
  },
});

Upgrade to CSF Next

You can upgrade your stories to CSF Next either automatically (from CSF 3) or manually (from CSF 1, 2, or 3). CSF Next is designed to be usable incrementally; you do not have to upgrade all of your story files at once. However, you cannot mix story formats within the same file.

Before proceeding, be sure you're using the latest version of Storybook. You can upgrade your Storybook automatically with this command:

npx storybook@next upgrade

Automatically

You can automatically upgrade all of your project's stories from CSF 3 to CSF Next with this command:

npx storybook automigrate csf-factories

It will run through each of the manual upgrade steps below on all of your story files.

npx storybook migrate csf-2-to-3 --glob="**/*.stories.tsx" --parser=tsx

Manual

You can also upgrade your project's story files to CSF Next manually. Before using CSF Next in a story file, you must upgrade your .storybook/main.js|ts and .storybook/preview.js|ts files.

1. Update your main Storybook config file

Update your .storybook/main.js|ts file to use the new defineMain function.

// Replace your-framework with the framework you are using (e.g., react-vite, nextjs, nextjs-vite)
+ import { defineMain } from '@storybook/your-framework/node';
- import { StorybookConfig } from '@storybook/your-framework';
 
+ export default defineMain({
- export const config: StorybookConfig = {
    // ...config itself is unchanged
+ });
- };
- export default config;

2. Update your preview config file

Update your .storybook/preview.js|ts file to use the new definePreview function.

// Replace your-framework with the framework you are using (e.g., react-vite, nextjs, nextjs-vite)
+ import { definePreview } from '@storybook/your-framework';
- import type { Preview } from '@storybook/your-framework';
// 👇 Import the addons you are using
+ import addonA11y from '@storybook/addon-a11y';
 
+ export default definePreview({
- export const preview: Preview = {
    // ...current config
    // 👇 Add your addons here
+   addons: [addonA11y()],
+ });
- };
- export default preview;

3. Update your story files

Story files have been updated for improved usability. With the new format:

• Import the preview construct from the Storybook preview file
• The meta object is now created via the preview.meta function and does not have to be exported as a default export
• Stories are now created from the meta object, via the meta.story function

+ import preview from '../.storybook/preview';
- import type { Meta, StoryObj } from '@storybook/your-framework';
 
import { Button } from './Button';
 
+ const meta = preview.meta({
- const meta = {
    // ...meta object is unchanged
+ });
- } satisfies Meta<typeof Button>;
- export default meta;
 
- type Story = StoryObj<typeof meta>;
 
+ export const Primary = meta.story({
- export const Primary: Story = {
    // ...story object is unchanged
+ });
- };

Note that importing or manually applying any type to the meta or stories is no longer necessary. Thanks to the factory function pattern, the types are now inferred automatically.

3.1 Reusing story properties

Previously, story properties such as Story.args or Story.parameters were accessed directly when reusing them in another story. While accessing them like this is still supported, it is deprecated in CSF Next.

All of the story properties are now contained within a new property called composed and should be accessed from that property instead. For instance, Story.composed.args or Story.composed.parameters.

// ...rest of file
 
+ export const Primary = meta.story({
- export const Primary: Story = {
    args: { primary: true },
+ });
- };
 
+ export const PrimaryDisabled = meta.story({
- export const PrimaryDisabled: Story = {
    args: {
+     ...Primary.composed.args,
-     ...Primary.args,
      disabled: true,
    }
+ });
- };

4. Update your Vitest setup file

If you're using Storybook's Vitest addon, you can remove your Vitest setup file (.storybook/vitest.setup.ts).

If you are using portable stories in Vitest, you may use a Vitest setup file to configure your stories. This file must be updated to use the new CSF Next format.

import { beforeAll } from 'vitest';
// 👇 No longer necessary
- // Replace your-framework with the framework you are using, e.g. react-vite, nextjs, nextjs-vite, etc.
import { setProjectAnnotations } from '@storybook/your-framework';
- import * as addonAnnotations from 'my-addon/preview';
+ import preview from './.storybook/preview';
- import * as previewAnnotations from './.storybook/preview';
 
// No longer necessary
- const annotations = setProjectAnnotations([previewAnnotations, addonAnnotations]);
 
// Run Storybook's beforeAll hook
+ beforeAll(preview.composed.beforeAll);
- beforeAll(annotations.beforeAll);

5. Reusing stories in test files

Storybook's Vitest addon allows you to test your components directly inside Storybook. All the stories are automatically turned into Vitest tests, making integration seamless in your testing suite.

If you cannot use Storybook Test, you can still reuse the stories in your test files using portable stories. In prior story formats, you had to compose the stories before rendering them in your test files. With CSF Next, you can now reuse the stories directly.

import { test, expect } from 'vitest';
import { screen } from '@testing-library/react';
- import { composeStories } from '@storybook/your-framework';
 
// Import all stories from the stories file
import * as stories from './Button.stories';
 
+ const { Primary } = stories;
- const { Primary } = composeStories(stories);
 
test('renders primary button with default args', async () => {
  // The run function will mount the component and run all of Storybook's lifecycle hooks
  await Primary.run();
  const buttonElement = screen.getByText('Text coming from args in stories file!');
  expect(buttonElement).not.toBeNull();
});

The Story object also provides a Component property, enabling you to render the component with any method you choose, such as Testing Library. You can also access its composed properties (args, parameters, etc.) via the composed property.

Here's an example of how you can reuse a story in a test file by rendering its component:

import { test, expect } from 'vitest';
import { render, screen } from '@testing-library/react';
 
// Import all stories from the stories file
import * as stories from './Button.stories';
 
const { Primary, Secondary } = stories;
 
test('renders primary button with default args', async () => {
  // Access the story's component via the .Component property
  render(<Primary.Component />);
  const buttonElement = screen.getByText('Text coming from args in stories file!');
  expect(buttonElement).not.toBeNull();
});
 
test('renders primary button with overridden props', async () => {
  // You can override props by passing them directly to the story's component
  render(<Primary.Component>Hello world</Primary.Component>);
  const buttonElement = screen.getByText(/Hello world/i);
  expect(buttonElement).not.toBeNull();
});

Frequently asked questions (FAQ)

Will I have to migrate all of my stories to this new format?

Storybook will continue to support CSF 1, CSF 2, and CSF 3 for the foreseeable future. None of these prior formats are deprecated.

While using CSF Next, you can still use the older formats, as long as they are not mixed in the same file. If you want to migrate your existing files to the new format, refer to the upgrade section, above.

Will this format work with MDX docs pages?

Yes, the doc blocks used to reference stories in MDX files support the CSF Next format with no changes needed.

How can I know more about this format and provide feedback?

For more information on this experimental format's original proposal, refer to its RFC on GitHub. We welcome your comments!