memfs

Creating and manipulating files

This feature allows you to create, read, and write files in memory as if you were using the native fs module.

const { Volume } = require('memfs');
const vol = new Volume();
vol.writeFileSync('/hello.txt', 'Hello, World!');
const content = vol.readFileSync('/hello.txt', 'utf8');
console.log(content); // Outputs: Hello, World!

Directory operations

This feature enables you to create directories, list their contents, and perform other directory-related operations, all in memory.

const { Volume } = require('memfs');
const vol = new Volume();
vol.mkdirSync('/mydir');
vol.writeFileSync('/mydir/file.txt', 'My file content');
const files = vol.readdirSync('/mydir');
console.log(files); // Outputs: ['file.txt']

Linking and symlinking

This feature allows you to create hard links and symbolic links, mimicking the behavior of links on a real file system.

const { Volume } = require('memfs');
const vol = new Volume();
vol.writeFileSync('/original.txt', 'Content of original');
vol.linkSync('/original.txt', '/link.txt');
vol.symlinkSync('/original.txt', '/symlink.txt');
const linkContent = vol.readFileSync('/link.txt', 'utf8');
const symlinkContent = vol.readlinkSync('/symlink.txt');
console.log(linkContent); // Outputs: Content of original
console.log(symlinkContent); // Outputs: /original.txt

File system watching

This feature provides the ability to watch for changes in the file system, similar to fs.watch in the native fs module.

const { Volume } = require('memfs');
const vol = new Volume();
const fs = vol.promises;

async function watchExample() {
  await fs.writeFile('/watched.txt', 'Initial content');
  fs.watch('/watched.txt', (eventType, filename) => {
    console.log(`Event type: ${eventType}; File: ${filename}`);
  });
  await fs.writeFile('/watched.txt', 'Updated content');
}

watchExample();