sindresorhus / has-yarn

Check if a project is using Yarn

has-yarn

Check if a project is using Yarn

Useful for tools that needs to know whether to use yarn or npm to install dependencies.

It checks if a yarn.lock file is present in the working directory.

Install

$ npm install has-yarn

Usage

.
├── foo
│   └── package.json
└── bar
    ├── package.json
    └── yarn.lock

import hasYarn from 'has-yarn';

hasYarn('foo');
//=> false

hasYarn('bar');
//=> true

API

hasYarn(cwd?)

Returns a boolean of whether the project uses Yarn.

cwd

Type: string
Default: process.cwd()

The current working directory.

Related

• has-yarn-cli - CLI for this module

has-yarn's Issues

Add documentation explaining checking

Hi @sindresorhus, nice module as always.

It would probably be good to add a bit of explanation about how this is checking if something is using yarn. The module is small enough that most people can read it themselves, but just explaining "it checks for a yarn.lock" in the readme might be good.

Add support for Yarn workspaces

This package assumes yarn.lock is in cwd folder, which is not always the case for Yarn workspaces, and result will depend on how you run the command:

• yarn workspace my-package xyz => hasYarn=true
• cd packages/my-package && yarn xyz => hasYarn=false

I suggest to also look for a Yarn workspace in parent folders, and look for a lock file there too

Usable as cli command?

I love latest-version which is usable as CLI command as well through the ported package called latest-version-cli.

I often forget if my packages I'm working on use Yarn or NPM and if I could just do a quick check from the terminal with a command has-yarn and it returns true or false for that repo, that would be really helpful!