memfs

memfs

In-memory file-system with Node's fs API.

• Node's fs API implemented, see old API Status, missing list, missing opendir
• Stores files in memory, in Buffers
• Throws sameish* errors as Node.js
• Has concept of i-nodes
• Implements hard links
• Implements soft links (aka symlinks, symbolic links)
• Permissions may* be implemented in the future
• Can be used in browser, see memfs-webpack

Install

npm install --save memfs

Usage

import { fs } from 'memfs'; fs.writeFileSync('/hello.txt', 'World!'); fs.readFileSync('/hello.txt', 'utf8'); // World!

Create a file system from a plain JSON:

import { fs, vol } from 'memfs'; const json = { './README.md': '1', './src/index.js': '2', './node_modules/debug/index.js': '3', }; vol.fromJSON(json, '/app'); fs.readFileSync('/app/README.md', 'utf8'); // 1 vol.readFileSync('/app/src/index.js', 'utf8'); // 2

Export to JSON:

vol.writeFileSync('/script.sh', 'sudo rm -rf *'); vol.toJSON(); // {"/script.sh": "sudo rm -rf *"}

Use it for testing:

vol.writeFileSync('/foo', 'bar'); expect(vol.toJSON()).toEqual({ '/foo': 'bar' });

Create as many filesystem volumes as you need:

import { Volume } from 'memfs'; const vol = Volume.fromJSON({ '/foo': 'bar' }); vol.readFileSync('/foo'); // bar const vol2 = Volume.fromJSON({ '/foo': 'bar 2' }); vol2.readFileSync('/foo'); // bar 2

Use memfs together with unionfs to create one filesystem from your in-memory volumes and the real disk filesystem:

import * as fs from 'fs'; import { ufs } from 'unionfs'; ufs.use(fs).use(vol); ufs.readFileSync('/foo'); // bar

Use fs-monkey to monkey-patch Node's require function:

import { patchRequire } from 'fs-monkey'; vol.writeFileSync('/index.js', 'console.log("hi world")'); patchRequire(vol); require('/index'); // hi world

Docs

• Reference
• Relative paths
• API status
• Dependencies

See also

• spyfs - spies on filesystem actions
• unionfs - creates a union of multiple filesystem volumes
• linkfs - redirects filesystem paths
• fs-monkey - monkey-patches Node's fs module and require function
• libfs - real filesystem (that executes UNIX system calls) implemented in JavaScript

License

Unlicense - public domain.