@friendofsvelte/mermaid

A powerful, type-safe Mermaid.js component for Svelte 5 with SSR support, custom themes, and responsive design.

Features

• ⚡ Lightning Fast - Dynamic imports and optimized rendering
• 🎨 Fully Customizable - Complete theme control and configuration
• 📱 Responsive Ready - Built-in responsive behavior
• 🔒 Type Safe - Full TypeScript support with strict typing
• 🧪 Test Friendly - E2E tested with Playwright
• 🚀 SSR Compatible - Works with SvelteKit SSR and static generation

Installation

npm install @friendofsvelte/mermaid

Quick Start

<script>
  import { Mermaid } from '@friendofsvelte/mermaid';
  
  const diagram = `graph TD
    A[Start] --> B[Process]
    B --> C[End]`;
</script>

<Mermaid string={diagram} />

Advanced Usage

<script>
  import { Mermaid } from '@friendofsvelte/mermaid';
  import type { MermaidConfig } from '@friendofsvelte/mermaid';
  
  const config: MermaidConfig = {
    theme: 'dark',
    flowchart: {
      useMaxWidth: true,
      htmlLabels: true
    }
  };
  
  const diagram = `sequenceDiagram
    participant A as Alice
    participant B as Bob
    A->>B: Hello Bob!
    B-->>A: Hello Alice!`;
</script>

<Mermaid string={diagram} {config} />

API Reference

Props

Prop	Type	Required	Description
string	string	Yes	The Mermaid diagram definition string
config	MermaidConfig	No	Mermaid configuration options
error	Snippet<[MermaidError]>	No	Error display snippet

Types

interface MermaidConfig {
  theme?: 'default' | 'dark' | 'forest' | 'neutral' | 'base';
  flowchart?: {
    useMaxWidth?: boolean;
    htmlLabels?: boolean;
    curve?: string;
  };
  sequence?: {
    useMaxWidth?: boolean;
    actorMargin?: number;
  };
  // ... and more
}

interface MermaidError {
  message: string;
  stack?: string;
}

Supported Diagram Types

• Flowcharts - Process flows and decision trees
• Sequence Diagrams - API interactions and workflows
• Gantt Charts - Project timelines and scheduling
• User Journey Maps - UX flows and customer experience
• Entity Relationship Diagrams - Database schemas
• Git Graphs - Version control workflows
• Pie Charts - Data visualization
• Class Diagrams - Object-oriented design

Examples

Custom Theme

<script>
  import { Mermaid } from '@friendofsvelte/mermaid';
  
  const customConfig = {
    theme: 'dark',
    flowchart: {
      useMaxWidth: true,
      htmlLabels: true,
      curve: 'basis'
    }
  };
</script>

<Mermaid string={diagram} config={customConfig} />

Error Handling

<script>
  import { Mermaid } from '@friendofsvelte/mermaid';
  
  const invalidDiagram = `invalid syntax here`;
</script>

<Mermaid string={invalidDiagram}>
  {#snippet error(errorObj)}
    <div class="error-message">
      <p>Failed to render diagram: {errorObj.message}</p>
    </div>
  {/snippet}
</Mermaid>

Development

# Clone the repository
git clone https://github.com/friendofsvelte/mermaid.git
cd mermaid

# Install dependencies
npm install

# Start development server
npm run dev

# Run tests
npm run test

# Build library
npm run build

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

MIT © Friend of Svelte

Links

• Documentation
• Examples
• Issues
• Mermaid.js Documentation
• Svelte

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