JavaScript Executor

GitHub
JavaScript MCP Server

A JavaScript execution server for the Model Context Protocol (MCP), allowing AI models to run JavaScript code through MCP tool calls.

Features

  • JavaScript Execution: Run JavaScript code in one-time script execution mode
  • REPL Sessions: Maintain stateful REPL sessions across multiple interactions
  • TypeScript Support: Run TypeScript code with automatic transpilation
  • NPM Integration: Import and use npm packages dynamically
  • Interactive Mode: Direct command line REPL interface for interacting with the server
  • Named Pipe Interface: Use named pipes for communication with external processes

Installation

# Clone the repository
git clone https://github.com/yannbam/fresh-js-mcp.git
cd fresh-js-mcp

# Install dependencies
npm install

# Build the project
npm run build

Usage

# Start the MCP server in standard mode
npm start

# Start in interactive REPL mode
node dist/index.js --interactive

# Start with named pipe interface
node dist/index.js --pipe

# See all options
node dist/index.js --help

Operating Modes

The server supports three operating modes:

  1. Standard MCP Mode (default): Communicates via stdio using the Model Context Protocol
  2. Interactive Mode: Provides a REPL interface for direct user interaction
  3. Pipe Mode: Uses named pipes for communication with external processes

See the examples directory for detailed instructions on using these modes.

Available Tools

  • execute: Run JavaScript code once and return the result
  • createSession: Create a new REPL session
  • executeInSession: Execute code in an existing session
  • listSessions: List all active REPL sessions
  • deleteSession: Delete a REPL session

Development

# Run in development mode with hot reloading
npm run dev

# Lint the code
npm run lint

# Run tests
npm test

Architecture

The JavaScript MCP server follows a layered architecture:

  1. MCP Protocol Layer: Handles client communication
  2. JavaScript Execution Layer: Executes code in isolated environments
  3. Resource Management Layer: Manages packages and TypeScript
  4. Session Management Layer: Maintains REPL sessions with state persistence

License

MIT