yarn init

Interactively creates or updates a package.json file.

yarn init

This command walks you through an interactive session to create a package.json file. Some defaults such as the license and initial version are found in yarn’s init-* config settings.

Here’s an example of running the command inside of a directory named testdir:

$ yarn init

question name (testdir): my-awesome-package
question version (1.0.0):
question description: The best package you will ever find.
question entry point (index.js):
question git repository: https://github.com/yarnpkg/example-yarn-package
question author: Yarn Contributor
question license (MIT):
question private:
success Saved package.json
✨  Done in 87.70s.

This results in the following package.json:

{
  "name": "my-awesome-package",
  "version": "1.0.0",
  "description": "The best package you will ever find.",
  "main": "index.js",
  "repository": {
    "url": "https://github.com/yarnpkg/example-yarn-package",
    "type": "git"
  },
  "author": "Yarn Contributor",
  "license": "MIT"
}

By default, if answer given to question private is passed in as empty, the private key will not be added to package.json

If you already have an existing package.json file, then it will use the file’s entries as defaults.

The following existing package.json:

{
  "name": "my-existing-package",
  "version": "0.1",
  "description": "I exist therefore I am.",
  "repository": {
    "url": "https://github.com/yarnpkg/example-yarn-package",
    "type": "git"
  },
  "license": "BSD-2-Clause"
}

Results in the following defaults during the interactive session:

$ yarn init

question name (my-existing-package):
question version (0.1):
question description (I exist therefore I am.):
question entry point (index.js):
question git repository (https://github.com/yarnpkg/example-yarn-package):
question author: Yarn Contributor
question license (BSD-2-Clause):
question private:
success Saved package.json
✨  Done in 121.53s.

Setting defaults for yarn init

The following config variables can be used to customize the defaults for yarn init:

• init-author-name
• init-author-email
• init-author-url
• init-version
• init-license

yarn init --yes/-y

This command skips the interactive session mentioned above and generates a package.json based on your defaults. Some defaults may be modified changing init-* config settings like mentioned above. For example, given a fresh install of Yarn and inside a yarn-example directory:

$ yarn init --yes

warning The yes flag has been set. This will automatically answer yes to all questions which may have security implications.
success Saved package.json
✨  Done in 0.09s.

Which produces the following package.json:

{
  "name": "yarn-example",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT"
}

yarn init --private/-p

automatically add private: true to the package.json

$ yarn init --private

If the private flag is set, the private key will be automatically set to true and you still complete the rest of the init process.

question name (testdir): my-awesome-package
question version (1.0.0):
question description: The best package you will ever find.
question entry point (index.js):
question git repository: https://github.com/yarnpkg/example-yarn-package
question author: Yarn Contributor
question license (MIT):
success Saved package.json
✨  Done in 87.70s.

{
  "name": "my-awesome-package",
  "version": "1.0.0",
  "description": "The best package you will ever find.",
  "main": "index.js",
  "repository": {
    "url": "https://github.com/yarnpkg/example-yarn-package",
    "type": "git"
  },
  "author": "Yarn Contributor",
  "license": "MIT",
  "private": true
}

You can use both the yes and the private flags at the same time

Like this:

$ yarn init -yp

warning The yes flag has been set. This will automatically answer yes to all questions which may have security implications.
success Saved package.json
✨  Done in 0.05s.

Which produces the following package.json:

{
  "name": "yarn-example",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "private": true
}