This skill guides creation of comprehensive, well-structured Storybook stories for React components. Write production-ready stories with proper TypeScript types, interactive controls, and interaction tests.

The user provides a component to document in Storybook. They may specify particular states, variants, or interaction scenarios to cover.

Project Context

•Component Library: /components workspace
•Styling: Custom CSS with Nordic Minimal design system (see tokens.css)
•Icons: Custom SVG icons via Icon component from @finans/components
•Stories Location: Co-located with components (*.stories.tsx)
•Storybook Deployment: finans-components Azure App Service

Story Structure Fundamentals

Every Storybook story file follows this pattern:

•Imports: Component, types, decorators, and test utilities
•Meta Object: Component-level configuration (default export)
•Type Definition: type Story = StoryObj<typeof Component>
•Individual Stories: Named exports representing different states

Basic React Story Template

typescript

import type { Meta, StoryObj } from '@storybook/react';

import { YourComponent } from './YourComponent';

const meta: Meta<typeof YourComponent> = {
  component: YourComponent,
  title: 'Feature/YourComponent', // Optional: organize in sidebar
  tags: ['autodocs'], // Generates documentation automatically
};

export default meta;
type Story = StoryObj<typeof YourComponent>;

export const Default: Story = {
  args: {
    // Component props
  },
};

React-Specific Configuration

Decorator for Context Providers

Wrap components that need context (theme, auth, etc.):

typescript

import type { Meta, StoryObj } from '@storybook/react';
import { ThemeProvider } from '../providers/ThemeProvider';

const meta: Meta<typeof YourComponent> = {
  component: YourComponent,
  decorators: [
    (Story) => (
      <ThemeProvider>
        <Story />
      </ThemeProvider>
    ),
  ],
};

Global Decorators in preview.tsx

Configure in .storybook/preview.tsx for project-wide providers:

typescript

import type { Preview } from '@storybook/react';
import '../src/styles/tokens.css';
import '../src/styles/globals.css';

const preview: Preview = {
  decorators: [
    (Story) => (
      <div>
        <Story />
      </div>
    ),
  ],
  parameters: {
    backgrounds: {
      default: 'bone',
      values: [
        { name: 'bone', value: '#F5F2ED' },
        { name: 'warm-white', value: '#FDFCFA' },
        { name: 'dark', value: '#2C2C2C' },
      ],
    },
  },
};

export default preview;

Story-Specific Decorators

Apply decorators to individual stories when needed:

typescript

export const WithDarkTheme: Story = {
  args: { ... },
  decorators: [
    (Story) => (
      <div className="dark">
        <Story />
      </div>
    ),
  ],
};

Args and Controls

Args are the primary way to make stories interactive. They map directly to component props.

Defining Args

typescript

export const Primary: Story = {
  args: {
    label: 'Click me',
    disabled: false,
    variant: 'primary',
    size: 'medium',
  },
};

Customizing Controls with ArgTypes

Control the UI for editing args in Storybook:

typescript

const meta: Meta<typeof Button> = {
  component: Button,
  argTypes: {
    variant: {
      control: { type: 'radio' },
      options: ['primary', 'secondary', 'tertiary'],
      description: 'Visual style variant',
    },
    size: {
      control: { type: 'select' },
      options: ['small', 'medium', 'large'],
    },
    disabled: {
      control: 'boolean',
    },
    backgroundColor: {
      control: 'color',
    },
    onClick: {
      action: 'clicked', // Logs to Actions panel
    },
  },
};

Story Composition (Reusing Args)

Extend existing stories to reduce duplication:

typescript

export const Primary: Story = {
  args: {
    label: 'Primary Button',
    variant: 'primary',
  },
};

export const Secondary: Story = {
  args: {
    ...Primary.args,
    label: 'Secondary Button',
    variant: 'secondary',
  },
};

Actions and Event Handlers

Automatic Action Logging

Configure globally in .storybook/preview.tsx:

typescript

import type { Preview } from '@storybook/react';

const preview: Preview = {
  parameters: {
    actions: { argTypesRegex: '^on.*' }, // Logs all props starting with 'on'
  },
};

export default preview;

Manual Actions for Testing

Use fn() from storybook/test to create spies for interaction tests:

typescript

import { fn } from 'storybook/test';

const meta: Meta<typeof FormComponent> = {
  component: FormComponent,
  args: {
    onSubmit: fn(), // Can be asserted in play functions
  },
};

Interaction Testing with Play Functions

Play functions simulate user interactions and run assertions after the story renders.

Basic Interaction Test

typescript

import { fn, userEvent, within, expect } from 'storybook/test';

export const FilledForm: Story = {
  args: {
    onSubmit: fn(),
  },
  play: async ({ canvasElement, args }) => {
    const canvas = within(canvasElement);

    // Query the DOM using Testing Library
    const emailInput = canvas.getByLabelText('Email');
    const passwordInput = canvas.getByLabelText('Password');
    const submitButton = canvas.getByRole('button', { name: 'Submit' });

    // Simulate user interactions
    await userEvent.type(emailInput, 'user@example.com');
    await userEvent.type(passwordInput, 'password123');
    await userEvent.click(submitButton);

    // Assert behavior
    await expect(args.onSubmit).toHaveBeenCalled();
    await expect(canvas.getByText('Success!')).toBeInTheDocument();
  },
};

Common UserEvent Methods

All methods must be awaited:

typescript

await userEvent.click(element);
await userEvent.dblClick(element);
await userEvent.type(element, 'text', { delay: 100 });
await userEvent.hover(element);
await userEvent.tab();
await userEvent.keyboard('{Shift}{Tab}');
await userEvent.selectOptions(select, ['option1', 'option2']);
await userEvent.clear(input);

Grouping Interactions with Steps

Organize complex tests with descriptive steps:

typescript

import { within, userEvent, expect, step } from 'storybook/test';

export const ComplexFlow: Story = {
  play: async ({ canvasElement }) => {
    const canvas = within(canvasElement);

    await step('Fill in credentials', async () => {
      await userEvent.type(canvas.getByLabelText('Email'), 'user@example.com');
      await userEvent.type(canvas.getByLabelText('Password'), 'secret');
    });

    await step('Submit form', async () => {
      await userEvent.click(canvas.getByRole('button', { name: 'Login' }));
    });

    await step('Verify success message', async () => {
      await expect(canvas.getByText('Welcome!')).toBeInTheDocument();
    });
  },
};

Mocking and Spying

Use beforeEach to set up mocks:

typescript

import { fn } from 'storybook/test';

export const WithMockedData: Story = {
  args: {
    fetchUsers: fn(),
    onSubmit: fn(),
  },
  beforeEach: async ({ args }) => {
    // Mock return values
    args.fetchUsers.mockResolvedValue([
      { id: 1, name: 'Alice' },
      { id: 2, name: 'Bob' },
    ]);
  },
  play: async ({ canvasElement, args }) => {
    const canvas = within(canvasElement);

    // Wait for async data
    await canvas.findByText('Alice');

    // Interact and assert
    await userEvent.click(canvas.getByRole('button'));
    await expect(args.onSubmit).toHaveBeenCalledWith({
      userCount: 2,
      data: expect.anything(),
    });
  },
};

Component Patterns

Components with Children

For components that render children:

typescript

export const WithChildren: Story = {
  args: {
    title: 'Card Title',
  },
  render: (args) => (
    <Card {...args}>
      <p>This is child content</p>
      <button>Click me</button>
    </Card>
  ),
};

Components with Render Props

typescript

export const WithRenderProp: Story = {
  args: {
    renderItem: (item) => <span>{item.name}</span>,
    items: [{ name: 'Item 1' }, { name: 'Item 2' }],
  },
};

Multiple Component Variants

Document different states thoroughly:

typescript

export const Default: Story = { args: { ... } };
export const Loading: Story = { args: { isLoading: true } };
export const Error: Story = { args: { error: 'Something went wrong' } };
export const Empty: Story = { args: { items: [] } };
export const WithData: Story = { args: { items: mockData } };
export const Disabled: Story = { args: { disabled: true } };

Project-Specific Patterns

Using Custom CSS Components

typescript

import type { Meta, StoryObj } from '@storybook/react';
import { Button, Icon } from '@finans/components';

const meta: Meta<typeof Button> = {
  component: Button,
  tags: ['autodocs'],
};

export default meta;
type Story = StoryObj<typeof Button>;

export const Primary: Story = {
  args: {
    children: 'Primary Button',
    variant: 'primary',
  },
};

export const WithIcon: Story = {
  args: {
    children: 'Save',
    variant: 'primary',
    icon: <Icon name="check" size={18} />,
  },
};

Financial Data Components

For components displaying financial data (currency, percentages):

typescript

import type { Meta, StoryObj } from '@storybook/react';
import { HeroNumber } from './HeroNumber';

const meta: Meta<typeof HeroNumber> = {
  component: HeroNumber,
  title: 'Components/HeroNumber',
  tags: ['autodocs'],
  argTypes: {
    value: {
      control: 'number',
      description: 'Value in NOK (kroner)',
    },
    change: {
      control: 'number',
      description: 'Percentage change',
    },
    changeType: {
      control: { type: 'radio' },
      options: ['positive', 'negative', 'neutral'],
    },
  },
};

export default meta;
type Story = StoryObj<typeof HeroNumber>;

export const Default: Story = {
  args: {
    label: 'Netto formue',
    value: 1234567,
    change: 2.33,
    changeType: 'positive',
  },
};

export const NegativeChange: Story = {
  args: {
    ...Default.args,
    change: -1.5,
    changeType: 'negative',
  },
};

export const Milestone: Story = {
  args: {
    ...Default.args,
    value: 1000000,
    showMilestone: true,
  },
};

Chart Components with D3

typescript

import type { Meta, StoryObj } from '@storybook/react';
import { NetWorthChart } from './NetWorthChart';

const mockData = [
  { date: '01.01.2024', value: 950000 },
  { date: '01.02.2024', value: 980000 },
  { date: '01.03.2024', value: 1020000 },
];

const meta: Meta<typeof NetWorthChart> = {
  component: NetWorthChart,
  title: 'Components/Charts/NetWorthChart',
  parameters: {
    layout: 'padded',
  },
};

export default meta;
type Story = StoryObj<typeof NetWorthChart>;

export const Default: Story = {
  args: {
    data: mockData,
    width: 600,
    height: 300,
  },
};

export const Empty: Story = {
  args: {
    data: [],
    width: 600,
    height: 300,
  },
};

Best Practices

•One Story Per State: Each story should represent a distinct, meaningful state
•Meaningful Names: Use descriptive story names (not Story1, Story2)
•Args Over Hardcoding: Use args for all configurable properties
•Comprehensive Coverage: Document all important variants and edge cases
•Interaction Tests: Add play functions for critical user flows
•TypeScript Types: Use proper Meta and StoryObj types for type safety
•Documentation: Add descriptions to argTypes for better autodocs
•Actions for Events: Use fn() for callback props that need testing
•Accessibility: Test keyboard navigation and screen reader behavior
•Norwegian Context: Use Norwegian text in stories to match production UI

CSS Scoping

Always scope page-level CSS to avoid collisions with component library classes.

Problem: Unscoped selectors in page CSS override component styles globally.

css

/* BAD - leaks globally, overrides component library */
.page-header {
  margin-bottom: 64px;
}

/* GOOD - scoped to page */
.dashboard-page .page-header {
  margin-bottom: 64px;
}

Rules:

•Component library classes (in /components) define the base styles
•Page-level CSS should scope selectors to their parent container
•Use BEM naming (.block__element--modifier) to reduce collision risk
•When debugging unexpected styles, check for unscoped selectors in page CSS

Story Organization

typescript

const meta: Meta<typeof YourComponent> = {
  component: YourComponent,
  title: 'Features/Portfolio/YourComponent', // Nested in sidebar
  tags: ['autodocs'], // Auto-generate documentation page
};

// Basic states
export const Default: Story = { ... };
export const Empty: Story = { ... };
export const Loading: Story = { ... };

// Variants
export const Primary: Story = { ... };
export const Secondary: Story = { ... };

// Edge cases
export const WithLongText: Story = { ... };
export const WithError: Story = { ... };

// Interactive scenarios
export const UserCanSubmitForm: Story = {
  play: async ({ canvasElement }) => { ... },
};

Workflow

•Analyze Component: Review component props, state, and dependencies
•Set Up Meta: Configure component, decorators, and argTypes
•Define Stories: Create stories for all major states and variants
•Add Controls: Customize argTypes for better UX in Storybook UI
•Add Interactions: Write play functions for critical user flows
•Document: Add descriptions and examples for other developers
•Test: Run pnpm --filter components storybook and verify all stories

Running Storybook

bash

# Start Storybook development server
pnpm --filter components storybook

# Build Storybook for deployment
pnpm --filter components build-storybook

Remember: Great Storybook stories serve as both documentation and tests. They should be comprehensive, interactive, and easy to understand for other developers on the team.