# memfs

This is a fork of https://www.npmjs.com/package/memfs, since there's a bunch of critical bugs and missing maintenance there, which might not be a priority for that project, but are definitely a priority for me (though I'm sending PR's).   Upstream memfs has nearly 12 million downloads a week, so I can see why doing these changes would be really scary there!

Things I've done here include:

- update to newest jest, and increase maxWorkers for testing; fix an issue with one test
- update to newest typescript and node typings
- update target to es2020 from es5; this does make code run more efficiently and is much easier to debug if you want to directly edit node_modules
- fix the 13 security vulnerabilities revealed by npm audit
- upgrade prettier and switch to using the defaults
- switch to package-lock.json instead of yarn's lock
- fix chmodSync bug
- fix utimesSync bug
- fix realpathSync bug

See https://github.com/sagemathinc/memfs-js

---

## Upstream description

In-memory file-system with [Node's `fs` API](https://nodejs.org/api/fs.html).

- Node's `fs` API implemented, see [_old API Status_](./docs/api-status.md), [missing list](https://github.com/streamich/memfs/issues/735), [missing `opendir`](https://github.com/streamich/memfs/issues/663)
- Stores files in memory, in `Buffer`s
- 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`](https://github.com/streamich/memfs-webpack)

### Install

```shell
npm install --save memfs
```

## Usage

```js
import { fs } from "memfs";

fs.writeFileSync("/hello.txt", "World!");
fs.readFileSync("/hello.txt", "utf8"); // World!
```

Create a file system from a plain JSON:

```js
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:

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

Use it for testing:

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

Create as many filesystem volumes as you need:

```js
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`][unionfs] to create one filesystem
from your in-memory volumes and the real disk filesystem:

```js
import * as fs from "fs";
import { ufs } from "unionfs";

ufs.use(fs).use(vol);

ufs.readFileSync("/foo"); // bar
```

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

```js
import { patchRequire } from "fs-monkey";

vol.writeFileSync("/index.js", 'console.log("hi world")');
patchRequire(vol);
require("/index"); // hi world
```

## Docs

- [Reference](./docs/reference.md)
- [Relative paths](./docs/relative-paths.md)
- [API status](./docs/api-status.md)
- [Dependencies](./docs/dependencies.md)

## See also

- [`spyfs`][spyfs] - spies on filesystem actions
- [`unionfs`][unionfs] - creates a union of multiple filesystem volumes
- [`linkfs`][linkfs] - redirects filesystem paths
- [`fs-monkey`][fs-monkey] - monkey-patches Node's `fs` module and `require` function
- [`libfs`](https://github.com/streamich/full-js/blob/master/src/lib/fs.ts) - real filesystem (that executes UNIX system calls) implemented in JavaScript

[chat]: https://onp4.com/@vadim/~memfs
[chat-badge]: https://img.shields.io/badge/Chat-%F0%9F%92%AC-green?style=flat&logo=chat&link=https://onp4.com/@vadim/~memfs
[npm-url]: https://www.npmjs.com/package/memfs
[npm-badge]: https://img.shields.io/npm/v/memfs.svg
[travis-url]: https://travis-ci.org/streamich/memfs
[travis-badge]: https://travis-ci.org/streamich/memfs.svg?branch=master
[memfs]: https://github.com/streamich/memfs
[unionfs]: https://github.com/streamich/unionfs
[linkfs]: https://github.com/streamich/linkfs
[spyfs]: https://github.com/streamich/spyfs
[fs-monkey]: https://github.com/streamich/fs-monkey

## License

[Unlicense](./LICENSE) - public domain.