@yarnpkg/fslib

What is @yarnpkg/fslib?

@yarnpkg/fslib is a library that provides a set of utilities for working with the filesystem in a more abstract and high-level way. It is part of the Yarn package manager's ecosystem and is designed to facilitate file system operations, especially in the context of Yarn's plugin architecture.

What are @yarnpkg/fslib's main functionalities?

Path manipulation

This feature allows you to convert native paths to portable paths and vice versa. This is useful for ensuring that paths are consistent across different operating systems.

const { npath } = require('@yarnpkg/fslib');

const nativePath = npath.toPortablePath('/some/native/path');
console.log(nativePath); // Outputs: /some/native/path

File reading and writing

This feature provides asynchronous methods for reading and writing files. It simplifies file operations by providing promise-based APIs.

const { xfs } = require('@yarnpkg/fslib');

(async () => {
  const filePath = '/path/to/file.txt';
  await xfs.writeFilePromise(filePath, 'Hello, world!');
  const content = await xfs.readFilePromise(filePath, 'utf8');
  console.log(content); // Outputs: Hello, world!
})();

Directory operations

This feature allows you to perform directory operations such as creating directories and reading their contents. It supports recursive directory creation.

const { xfs } = require('@yarnpkg/fslib');

(async () => {
  const dirPath = '/path/to/directory';
  await xfs.mkdirPromise(dirPath, { recursive: true });
  const files = await xfs.readdirPromise(dirPath);
  console.log(files); // Outputs: list of files in the directory
})();

Other packages similar to @yarnpkg/fslib

fs-extra

fs-extra is a popular library that extends the native Node.js fs module with additional methods and promises. It provides similar functionalities to @yarnpkg/fslib, such as file and directory operations, but it is more general-purpose and not specifically tied to the Yarn ecosystem.

node-fs

node-fs is another library that extends the native fs module with additional features like recursive directory creation and symbolic link support. It offers similar capabilities to @yarnpkg/fslib but is less focused on path manipulation and more on enhancing the core fs module.

graceful-fs

graceful-fs is a drop-in replacement for the native fs module that improves its reliability, especially under heavy load. While it doesn't offer as many high-level utilities as @yarnpkg/fslib, it ensures more robust file system operations.

README

@yarnpkg/fslib

A TypeScript library abstracting the Node filesystem APIs. We use it for three main reasons:

Type-safe paths

Our library has two path types, NativePath and PortablePath. Most interfaces only accept the later, and instances of the former need to be transformed back and forth using our type-safe utilities before being usable.

Custom filesystems

The FSLib implements various transparent filesystem layers for a variety of purposes. For instance we use it in Yarn in order to abstract away the zip archive manipulation logic, which is implemented in ZipFS and exposed through a Node-like interface (called FakeFS).

All FakeFS implementations can be transparently layered on top of the builtin Node fs module, and that's for instance how we can add support for in-zip package loading without you having to care about the exact package format.

Promisified API

All methods from the FakeFS interface are promisified by default (and suffixed for greater clarity, for instance we offer both readFileSync and readFilePromise).