NDJSON Preview

A powerful VS Code extension for viewing and analyzing NDJSON (Newline Delimited JSON) files with syntax highlighting, filtering, and custom ordering capabilities.

Features

📊 Live Preview with Syntax Highlighting

• Side-by-side view: See pretty-printed JSON in a preview panel as you navigate through your NDJSON file
• Syntax highlighting: Color-coded JSON with distinct colors for keys, strings, numbers, booleans, and null values
• Auto-updates: Preview automatically updates as you move your cursor to different lines
• Line highlighting: Current line is highlighted in the editor for easy tracking

🔍 Advanced Filtering

• Filter by key-value pairs: Show only lines that match specific criteria
• Nested key support: Use dot notation (e.g., user.email, address.city) to filter on nested properties
• Multiple filters: Apply multiple filters with AND logic - lines must match all filters
• Filtered view: Creates a new editor tab showing only matching lines, perfect for large files
• Visual feedback: Shows count of matching lines (e.g., "Showing 45 of 1000 lines")

🔧 Custom JSON Ordering

• Reorder Keys toggle: Automatically sort JSON keys with primitives first, then objects/arrays
• Custom ordering: Define your own key order - specify which keys should appear first
• Persistent preferences: Custom order is saved globally and remembered between sessions
• Nested ordering: Ordering rules apply recursively to nested objects

Installation

From VSIX (Local Installation)

1. Download the .vsix file
2. Open VS Code
3. Go to Extensions (Ctrl+Shift+X / Cmd+Shift+X)
4. Click the ... menu → "Install from VSIX..."
5. Select the downloaded file

From VS Code Marketplace

1. Open VS Code
2. Go to Extensions (Ctrl+Shift+X / Cmd+Shift+X)
3. Search for "NDJSON Preview"
4. Click Install

Usage

Basic Usage

1. Open an NDJSON file (.ndjson or .jsonl)
2. Preview opens automatically in a side panel
3. Navigate lines - The preview updates as you move your cursor

Filtering Lines

1. Click the "Filter" button in the preview panel
2. Enter a key (e.g., status or user.name for nested keys)
3. Enter the value to match
4. Click "Add" or press Enter
5. Add more filters if needed
6. Click "Apply"

A new editor tab opens showing only lines that match all your filters. Click "Clear All" to remove filters and close the filtered view.

Example filters:

• status = active - Show only lines where status equals "active"
• user.role = admin - Show lines where user.role equals "admin"
• Multiple filters: type = order AND status = completed

Custom Key Ordering

Using the Reorder Toggle

Click the "Reorder Keys" toggle to automatically organize JSON with:

• Primitive values (strings, numbers, booleans, null) first
• Objects and arrays last

Using Custom Order

1. Click the "Custom Order" button
2. Enter one key per line in your desired order:

   id
   name
   email
   status
   

3. Click "Apply"

Keys will appear in the order you specified, followed by any remaining keys. This preference is saved globally.

Keyboard Shortcuts

In the filter modal:

• Enter in the key field - Move to value field
• Enter in the value field - Add the filter
• Esc - Close modal (click outside also works)

File Format

The extension works with NDJSON (Newline Delimited JSON) files where each line contains a valid JSON object:

{"id":1,"name":"Alice","age":30,"city":"New York","status":"active"}
{"id":2,"name":"Bob","age":25,"city":"Boston","status":"inactive"}
{"id":3,"name":"Charlie","age":35,"city":"Chicago","status":"active"}

Supported file extensions:

• .ndjson
• .jsonl

Configuration

Global Settings

• Custom Order: Saved globally in VS Code's global state
• Persists across sessions and workspaces

Per-Session Settings

• Filters: Reset when the preview panel is closed
• Reorder Keys toggle: Reset when the preview panel is closed

Use Cases

Log Analysis

Filter server logs by status code, user ID, or error type:

{"timestamp":"2024-01-15","level":"error","user_id":"123","message":"..."}
{"timestamp":"2024-01-15","level":"info","user_id":"456","message":"..."}

Filter: level = error to see only error logs

Data Exploration

Explore large datasets by filtering on specific attributes:

{"product":"laptop","category":"electronics","price":999,"stock":50}
{"product":"desk","category":"furniture","price":299,"stock":12}

Filter: category = electronics to view only electronics

API Response Analysis

Analyze API responses with consistent key ordering:

{"id":1,"data":{...},"metadata":{...},"status":"success"}

Custom order: id, status, data, metadata

Performance

• Efficient filtering: Handles files with thousands of lines
• Lazy rendering: Preview only renders the current line
• Lightweight: No heavy dependencies, uses VS Code's native capabilities

Development

Building from Source

# Clone the repository
git clone https://github.com/yourusername/ndjson-preview.git
cd ndjson-preview

# Install dependencies
npm install

# Compile
npm run compile

# Run in development mode (Press F5 in VS Code)

Project Structure

ndjson-preview/
├── src/
│   └── extension.ts    # Main extension code
├── package.json        # Extension manifest
├── tsconfig.json       # TypeScript configuration
└── README.md          # This file

Contributing

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

Known Issues

• Filtered view creates a new untitled document - changes to this document are not saved
• Very large JSON objects (>1MB per line) may cause performance issues in the preview

License

MIT

Release Notes

1.0.0

Initial release with:

• Live preview with syntax highlighting
• Line-by-line navigation
• Filter by key-value pairs
• Custom key ordering
• Nested key support with dot notation
• Persistent global preferences

Credits

• Built with pretty-print-json for syntax highlighting
• Developed for the VS Code community

Feedback & Support

• Issues: GitHub Issues
• Feature Requests: GitHub Discussions

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Enjoy analyzing your NDJSON files! 🚀