User-land implementation of the Node.js Virtual File System (VFS) based on nodejs/node#61478.

npm install node-vfs-polyfill

Requires Node.js >= 22.0.0

const { VirtualFS } = require('node-vfs-polyfill');

const vfs = new VirtualFS();
vfs.mkdirSync('/app');
vfs.writeFileSync('/app/index.js', 'console.log("hello")');
vfs.mount('/vfs');

// After mounting, use standard fs module
const fs = require('fs');
fs.readFileSync('/vfs/app/index.js'); // works

• In-memory file system with full fs API support
• Overlay mode for layering virtual files over real filesystem
• File descriptors, streams, and watch support
• Promise-based API via fs.promises
• Symlinks and glob patterns

• node-vfs-polyfill - Main VirtualFS class
• node-vfs-polyfill/provider - Base provider interface
• node-vfs-polyfill/memory-provider - In-memory storage provider

ISC

Code in vendor/vfs-upstream/ is from Node.js and subject to the Node.js license.