1. Configuration

Configuring your package

Yarn looks for package.json files to identify each package and configure the behavior of yarn while running inside that package.

An example configuration for the pet-kitten package, which would be found at pet-kitten/package.json:

{
  "name": "pet-kitten",
  "version": "0.1.0",
  "main": "pet.js",
  "dependencies": {
    "hand": "1.0.0"
  }
}

Use yarn.lock to pin your dependencies

Yarn also uses a yarn.lock file in the root of your project to make dependency resolution fast and reliable. You never need to touch this file- yarn owns it and will change it when managing dependencies.

To make sure your app works consistently, you should always save the yarn.lock file in your code repository.