Yarn Init Command: Create and Customize your package.json easily

The yarn init command is a command used to create or update a package.json file interactively.

yarn init

when you run this command from the terminal, it will walk you through an interactive session to create a package.json file. some of the defaults such as the license and initial version are found in the init-* config settings of yarn.

Here is an example of running the yarn init in a directory named movieapp:

yarn init v1.21.1
question name (movieapp):
question version (1.0.0):
question description: This is a sample movie application built with node
question entry point (index.js): app.js
question repository url:
question author: Aryan
question license (MIT):
question private: n
success Saved package.json
Done in 37.31s.

This will result in a package.json file with the following content:

{
  "name": "movieapp",
  "version": "1.0.0",
  "description": "This is a sample movie application built with node",
  "main": "app.js",
  "author": "Aryan ",
  "license": "MIT",
  "private": false
}

In the case where you already have an existing package.json file, yarn init will use the file's entries as defaults.

Given a package.json with the following package.json entries:

{
  "name": "movieapp",
  "version": "1.0.0",
  "description": "I was here",
  "main": "index.js",
  "author": "Awam ",
  "license": "MIT",
  "private": false
}

Running the yarn init command will yield the following defaults:

yarn init v1.21.1
question name (movieapp):
question version (1.0.0):
question description (I was here):
question entry point (index.js):
question repository url:
question author (Awam ):
question license (MIT):
question private:
success Saved package.json
Done in 15.07s.

Setting defaults for yarn init

You can use the following config variables to customize the defaults for yarn init.

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

yarn init --yes/-y

whenever you run this command, it will skip the interactive session and then generate a package.json based on your defaults.

Here is an example output from running yarn init:

yarn init v1.21.1
warning The yes flag has been set. This automatically answers yes to all questions, there may be security implications.
success Saved package.json
Done in 0.27s.

yarn init --private

Running the yarn init with the --private flag will set the private option to true.

As shown in below:

yarn init v1.21.1
question name (movieapp):
question version (1.0.0):
question description (I was here):
question entry point (index.js):
question repository url:
question author (Awam ):
question license (MIT):
question private (true):
success Saved package.json
Done in 8.24s.

The package.json file for the above output will be:

{
  "name": "movieapp",
  "version": "1.0.0",
  "description": "I was here",
  "main": "index.js",
  "author": "Awam ",
  "license": "MIT",
  "private": true
}

You can use both the private and yes flags at the same time. All you have to do is run:

yarn init -yp

This will automatically answer yes to all questions.

Previous: Mastering the Yarn Info command.
Next: Yarn Install commands.