mermaid2term

Render Mermaid diagrams as ASCII/Unicode art in the terminal.

┌───────┐
│       │
│ Start │
│       │
└───────┘
    │
    │
    │
┌───▼────┐
│        │
│ Process│
│        │
└────────┘
    │
    │ Yes
    ├────────────┐No
    │            │
┌───▼───┐   ┌────▼───┐
│       │   │        │
│  Done │   │  Skip  │
│       │   │        │
└───────┘   └────────┘

Installation

npm install -g mermaid2term

Or use directly with npx:

npx mermaid2term diagram.mmd

Usage

CLI

# From a file
mermaid2term diagram.mmd

# From stdin
echo 'graph LR; A-->B; B-->C' | mermaid2term

# With options
mermaid2term --charset ascii diagram.mmd

Options

| Option | Description | Default | |--------|-------------|---------| | -c, --charset <type> | Character set: unicode or ascii | unicode | | -h, --help | Show help | | | -V, --version | Show version | |

Programmatic API

import { render } from 'mermaid2term';

const diagram = `
graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Do Something]
    B -->|No| D[Skip]
    C --> E[End]
    D --> E
`;

const output = render(diagram);
console.log(output);

API Reference

render(input: string, options?: RenderOptions): string

Renders a Mermaid diagram to ASCII/Unicode art.

Parameters:

• input - Mermaid diagram source
• options - Optional configuration object

Options:

interface RenderOptions {
  charset?: 'unicode' | 'ascii';  // Default: 'unicode'
  paddingX?: number;              // Horizontal padding between nodes (default: 4)
  paddingY?: number;              // Vertical padding between nodes (default: 2)
  borderPadding?: number;         // Padding inside node borders (default: 1)
}

Supported Diagram Types

Flowcharts

Full support for flowchart/graph diagrams:

graph TD
    A[Rectangle] --> B(Rounded)
    B --> C{Diamond}
    C -->|Yes| D[Result 1]
    C -->|No| E[Result 2]

Supported features:

• Directions: TD/TB (top-down), LR (left-right), RL (right-left), BT (bottom-top)
• Node shapes: rectangles [], rounded (), diamonds {}
• Edge types: solid -->, dotted -..->, thick ==>
• Edge labels: -->|label|
• Cycles/back-edges (rendered with proper routing)
• Semicolon syntax for single-line diagrams

Example:

echo 'graph LR; A-->B; B-->C; C-->A' | mermaid2term

Output:

┌───┐     ┌───┐     ┌───┐
│   │     │   │     │   │
│ A │─────► B │─────► C │
│   │     │   │     │   │
└─▲─┘     └───┘     └───┘
  │                   │
  └───────────────────┘

Sequence Diagrams

Basic support for sequence diagrams:

sequenceDiagram
    Alice->>Bob: Hello Bob
    Bob-->>Alice: Hi Alice

Character Sets

Unicode (default)

Uses Unicode box-drawing characters for crisp rendering:

┌───────┐
│ Node  │
└───────┘
    │
    ▼

ASCII

For terminals without Unicode support:

+-------+
| Node  |
+-------+
    |
    v

Examples

Decision Flow

echo 'graph TD
    Start --> Process
    Process --> Decision{Valid?}
    Decision -->|Yes| Success
    Decision -->|No| Error
    Error --> Process
    Success --> End' | mermaid2term

Horizontal Flow

echo 'graph LR
    Input --> Process
    Process --> Output' | mermaid2term

With Labels

echo 'graph TD
    A -->|step 1| B
    B -->|step 2| C
    C -->|step 3| D' | mermaid2term

Development

# Clone the repository
git clone https://github.com/watzon/mermaid2term.git
cd mermaid2term

# Install dependencies
npm install

# Build
npm run build

# Run tests
npm test

# Development mode (watch)
npm run dev

License

MIT