JavaScript VM

A secure, isolated JavaScript VM for Node.js, built with TypeScript. Developed and maintained as an open source project by ChatFinAI.

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Features

• Run untrusted JavaScript code securely in an isolated VM
• TypeScript-first development
• Uses isolated-vm for sandboxing
• WebSocket inspector support for debugging
• Extensible sandbox API

Getting Started

Prerequisites

• Node.js >= 18
• npm >= 9

Installation

From npm (Recommended)

npm install @chatfinai/javascript-vm

From source

Clone the repository and install dependencies:

git clone https://github.com/ChatFinAI/javascript-vm.git
cd javascript-vm
npm install

Build

npm run build

Development

Run the sample calculator example:

npm run dev

Debugging

Node.js Debugger

You can debug the TypeScript code using VS Code or any Node.js debugger:

node --inspect-brk -r ts-node/register src/index.ts

Then attach your debugger to localhost:9229.

WebSocket Inspector (VM Debugging)

To enable the VM inspector, instantiate ExecSandbox with debug=true and specify a port (default: 3000):

const sandbox = new ExecSandbox({}, true, 3000);

This starts a WebSocket inspector server. You can connect Chrome DevTools to:

devtools://devtools/bundled/inspector.html?experiments=true&v8only=true&ws=127.0.0.1:3000

for live debugging of the isolated VM context.

Type Checking

npm run type-check

Usage Example

TypeScript

import { ExecSandbox, GenDictionary } from '@chatfinai/javascript-vm';

const calculatorCode = `
  function add(a, b) { return a + b; }
  function subtract(a, b) { return a - b; }
  function multiply(a, b) { return a * b; }
  function divide(a, b) { return a / b; }
  result = {
    add: add(5, 3),
    subtract: subtract(5, 3),
    multiply: multiply(5, 3),
    divide: divide(5, 3)
  };
`;

async function runCalculatorSandbox() {
  const sandbox = new ExecSandbox(false);
  try {
    const output = await sandbox.run(calculatorCode, {} as GenDictionary);
    console.log("Calculator Results:", output.result);
  } catch (err) {
    console.error("Sandbox error:", err);
  } finally {
    sandbox.dispose();
  }
}

runCalculatorSandbox();

JavaScript (CommonJS)

const { ExecSandbox } = require('@chatfinai/javascript-vm');

const calculatorCode = `
  function add(a, b) { return a + b; }
  function subtract(a, b) { return a - b; }
  function multiply(a, b) { return a * b; }
  function divide(a, b) { return a / b; }
  result = {
    add: add(5, 3),
    subtract: subtract(5, 3),
    multiply: multiply(5, 3),
    divide: divide(5, 3)
  };
`;

async function runCalculatorSandbox() {
  const sandbox = new ExecSandbox(false);
  try {
    const output = await sandbox.run(calculatorCode, {});
    console.log("Calculator Results:", output.result);
  } catch (err) {
    console.error("Sandbox error:", err);
  } finally {
    sandbox.dispose();
  }
}

runCalculatorSandbox();

Project Structure

• src/VM/ — Core VM and sandbox classes
• src/Models/ — Type definitions
• src/index.ts — Main exports for npm package
• examples/ — Calculator usage examples (JavaScript and TypeScript)

Examples

The examples/ directory contains calculator examples showing how to use the VM:

• calculator.js — JavaScript (CommonJS) example
• calculator.ts — TypeScript example with proper types

Running Examples

If you installed from npm:

npm install @chatfinai/javascript-vm

Then update the import statements in the examples:

• In calculator.js: Change require('../dist/index.js') to require('@chatfinai/javascript-vm')
• In calculator.ts: Change from '../src/index' to from '@chatfinai/javascript-vm'

# Run JavaScript example
node examples/calculator.js

# Run TypeScript example
npx ts-node examples/calculator.ts

If you're running from source:

# First, build the project
npm run build

# Run JavaScript example (uses dist/index.js)
node examples/calculator.js

# Run TypeScript example (uses src/index.ts)
npx ts-node examples/calculator.ts

License

This project is licensed under the MIT License. See the LICENSE file for details.

Maintainers

• ChatFinAI Open Source Team (support@chatfin.ai)

Support

For questions or support, open an issue on GitHub or contact us at support@chatfin.ai.