How do you use Svelte with Storybook

Storybook is a popular tool for developing and testing user interface components in isolation. It provides a sandbox environment where you can build and showcase components independently of your application. Integrating Storybook with Svelte allows you to leverage these benefits within the Svelte ecosystem, enabling you to create, test, and document your Svelte components more effectively. This article will guide you through setting up Storybook with Svelte and using it to develop and showcase your Svelte components.

Introduction to Storybook

What is Storybook?

Storybook is an open-source tool for developing UI components in isolation. It enables you to build, test, and document components separately from your application, providing a focused environment for component development. Key features of Storybook include:

Component Isolation: Develop and test components without the need for a full application context.
Interactive UI: View and interact with your components in a live environment.
Documentation: Automatically generate and maintain documentation for your components.
Add-ons: Extend Storybook’s functionality with a rich ecosystem of add-ons for testing, accessibility, and more.

Setting Up Storybook with Svelte

Prerequisites

Before setting up Storybook with Svelte, ensure you have the following prerequisites:

Node.js and npm (or yarn) installed
A Svelte project set up

If you don’t have a Svelte project yet, you can create one using the following command:

npx degit sveltejs/template svelte-storybook
cd svelte-storybook
npm install

Installing Storybook

To add Storybook to your Svelte project, follow these steps:

Install Storybook CLI

First, install the Storybook CLI globally if you haven’t already:
```
npm install -g @storybook/cli
```
Initialize Storybook

Navigate to your Svelte project directory and initialize Storybook:
```
npx sb init
```
This command will set up Storybook and create a .storybook directory in your project.
Install Svelte Add-ons

You’ll need the @storybook/svelte package to integrate Storybook with Svelte:
```
npm install --save-dev @storybook/svelte
```
Additionally, you may want to install the svelte and svelte-loader packages:
```
npm install --save-dev svelte svelte-loader
```

Configure Storybook

Update your Storybook configuration to work with Svelte. In the .storybook directory, modify main.js to include the Svelte configuration:

// .storybook/main.js
module.exports = {
  stories: ['../src/**/*.stories.svelte'],
  addons: ['@storybook/addon-links', '@storybook/addon-essentials'],
  framework: '@storybook/svelte',
};

Create a preview.js file in the .storybook directory to configure Storybook’s preview settings:

// .storybook/preview.js
import '../src/styles/global.css'; // Import global styles if any

export const parameters = {
  actions: { argTypesRegex: "^on[A-Z].*" },
  controls: { expanded: true },
};

Creating Your First Story

With Storybook set up, you can now create your first story. A story represents a single state of a component. Here’s how to create a basic story for a Svelte component:

Create a Svelte Component

Let’s create a simple button component. Create a file Button.svelte in the src directory:

<!-- src/Button.svelte -->
<script>
  export let label = 'Click me';
</script>

<button>{label}</button>

Create a Story for the Component

Next, create a story file for the Button component. Create a file Button.stories.svelte in the src directory:
```

<script>
  import Button from './Button.svelte';
</script>

<h2>Button</h2>

<Button label="Default Button" />
<Button label="Primary Button" style="background-color: blue; color: white;" />
```
In this story, we import the Button component and render it with different props to showcase its different states.
Run Storybook

Start the Storybook development server to view your stories:
```
npm run storybook
```
Open your browser and navigate to http://localhost:6006 to see your Svelte component in Storybook.

Advanced Usage

Using Add-ons

Storybook has a rich ecosystem of add-ons that can enhance your development experience. Here are some popular add-ons and how to use them with Svelte:

@storybook/addon-actions

The actions add-on helps you monitor the actions your components are performing. Install it with:

npm install --save-dev @storybook/addon-actions

Update your .storybook/main.js to include the actions add-on:

// .storybook/main.js
module.exports = {
  stories: ['../src/**/*.stories.svelte'],
  addons: ['@storybook/addon-links', '@storybook/addon-essentials', '@storybook/addon-actions'],
  framework: '@storybook/svelte',
};

Use the action function in your stories to log actions:

<!-- src/Button.stories.svelte -->
<script>
  import { action } from '@storybook/addon-actions';
  import Button from './Button.svelte';
</script>

<h2>Button</h2>

<Button on:click={action('button-click')} label="Click me" />

@storybook/addon-knobs

The knobs add-on allows you to dynamically edit props of your components in the Storybook UI. Install it with:

npm install --save-dev @storybook/addon-knobs

Update your .storybook/main.js to include the knobs add-on:

// .storybook/main.js
module.exports = {
  stories: ['../src/**/*.stories.svelte'],
  addons: ['@storybook/addon-links', '@storybook/addon-essentials', '@storybook/addon-knobs'],
  framework: '@storybook/svelte',
};

Use the withKnobs decorator in your stories to add interactive knobs:

<!-- src/Button.stories.svelte -->
<script>
  import { withKnobs, text } from '@storybook/addon-knobs';
  import Button from './Button.svelte';
</script>

export default {
  title: 'Button',
  decorators: [withKnobs],
};

export const Default = () => ({
  Component: Button,
  props: {
    label: text('Label', 'Click me'),
  },
});

Writing Stories in Different Formats

Storybook supports various formats for writing stories, including:

Component Story Format (CSF)

CSF is a popular format for writing stories, where each story is exported as a named export from a .stories.js or .stories.svelte file.

// src/Button.stories.js
import Button from './Button.svelte';

export default {
  title: 'Button',
  component: Button,
};

export const Default = () => ({
  Component: Button,
  props: {
    label: 'Click me',
  },
});

export const Primary = () => ({
  Component: Button,
  props: {
    label: 'Primary Button',
  },
  styles: {
    backgroundColor: 'blue',
    color: 'white',
  },
});

Storybook Docs

Storybook Docs provides a way to write documentation for your components alongside your stories. Install the @storybook/addon-docs package:

npm install --save-dev @storybook/addon-docs

Update your .storybook/main.js to include the docs add-on:

// .storybook/main.js
module.exports = {
  stories: ['../src/**/*.stories.svelte'],
  addons: ['@storybook/addon-links', '@storybook/addon-essentials', '@storybook/addon-docs'],
  framework: '@storybook/svelte',
};

Write documentation in your story files using MDX (Markdown for JSX):

<!-- src/Button.stories.mdx -->
import { Meta, Story, Preview } from '@storybook/addon-docs';
import Button from './Button.svelte';

<Meta title="Button" component={Button} />

# Button Component

The `Button` component is used to render a button.

<Preview>
  <Story name="Default">
    <Button label="Click me" />
  </Story>
  <Story name="Primary">
    <Button label="Primary Button" style="background-color: blue; color: white;" />
  </Story>
</Preview>

Best Practices

Keep Stories Focused

Write stories that focus on a single aspect or state of a component. This makes it easier to test and understand each component’s behavior.
**Use Knobs for Dynamic

Props**

Use the knobs add-on to allow dynamic editing of component props. This can help you test different scenarios without modifying your story files.

Document Your Components

Take advantage of Storybook Docs to provide detailed documentation for your components. This helps other developers understand how to use and integrate them.
Organize Your Stories

Organize your stories in a logical structure, such as grouping related components together. This makes it easier to navigate and maintain your Storybook.
Test Component Interactions

Use add-ons like actions to test and monitor interactions between components. This helps ensure your components work as expected in different scenarios.

Conclusion

Integrating Storybook with Svelte provides a powerful environment for developing, testing, and documenting your components. By setting up Storybook and using its features, you can create high-quality Svelte components, test their behavior in isolation, and generate comprehensive documentation.

With the ability to render components in isolation, test interactions, and document usage, Storybook enhances your development workflow and improves the overall quality of your UI components. By following the steps outlined in this article, you can effectively use Storybook with Svelte to build and showcase your components with confidence.

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