npm – How to create a private npm?

Use case: You have your own React UI library project and you want to use UI components from this lib across other projects

React Native:
publish-your-react-native-package-to-npm
publish-your-first-react-native-npm

React Web:
publishing-a-react-package-to-npm

How to locally install your module project into your app?

Pack your module project

• Open your module project and run

yarn pack

You will get a compressed file like myreactnativelib-v0.0.1.tgz

• Open your React app project and run yarn add this compressed file

yarn add /Volumes/data/user/react-native-my-lib/myreactnativelib-v0.0.1.tgz

then, you can see module project is installed inside node_modules folder

How to reuse dependencies in app project for module project?

• Use peerDependencies in your module project
• peerDependencies are not included in built module
• peerDependencies are dependencies that the host app is expected to provide
• When to use peerDependencies?
  • If dependency that will almost certainly also be a core dependency of those other applications. Ex: React dependency

"peerDependencies": {
  "react": "^17.0.1",
  "react-dom": "^17.0.1"
}

How to specify peer dependencies version?

• npm package version is set as semantic versioning: major.minor.patch
• Use tilde (~) to allow newer patch, caret (^) to allow newer minor level versions of a package
• Specify the versions of a peer dependency that our package can work with, rather than the version we’d prefer to use

// can work with react 16.8 to react 17
"peerDependencies": {
  "react": "16.8 - 17"
}

Why is it error when building module project?

• When you use peer dependencies, npm will not install those dependencies
• This leads to errors when you are running tests on your package
• To void this, include the peer dependencies as dev dependencies
  That way, they will be available for local testing but will still be peer dependencies in the published npm module