Node.js and Yarn for Happy Local Package Development

This is not another praise piece for npm package management with Yarn, but rather a concise recipe for working with locally developed packages.

npm modules begin their lives when you init them on your local dev machine, but there comes a point when you want to test them out or simply use them with other Node.js projects you have.

With the npm client, you would be creating a link in the filesystem, but with Yarn you can really manage their versioning and use them just like any other dependency with all the rules applied for dependencies.

Modules on the Filesystem: yarn add file://

Use the following command to add a package from the filesystem:

yarn add file:/Users/lirantal/code/my-npm-module

Some things that are good to keep in mind when doing the above:

• Because Yarn treats this as a real dependency, it means that it will really install it to your local node_modules/ directory, so if you make changes on the npm module, they won't be reflected on the installed version you have in the Node.js project.

• Yarn loves cache and it also caches those local npm modules. You can force a re-install by doing the following:

#Remove the package and clean local cache

yarn remove my-npm-mdule

yarn cache clean

#Re-install it

yarn add file:/...

Modules on GitHub/Git

Another thing that comes in handy with Yarn is that you can push your npm modules to a Git repository and tell Yarn to use that. This is useful if you don't want to submit the npm package to an npm repository.

This is not specific to Yarn. The npm client can do the same thing. If you have a package on GitHub you can tell Yarn to install it by using the folowing command:

yarn add git+ssh://[email protected]/lirantal/my-npm-module.git

The same caching and versioning applies here as it did for the filesystem install.