Example Typescript Monorepo

This project represents a minimal example that uses Lerna to structure a Typescript monorepo with multiple packages and some dependencies between the packages. Shown below is the dependency graph between the packages in this project:

Usage

• npx lerna run build to build all packages and their dependencies.
• npx lerna run build --scope @js-monorepo/useful to build just the packages/useful package.

Using Packages Locally

This is mostly needed when you are making changes locally and would like to have a fast development loop to test the results of your changes.

Within This Project

If you would like to establish a dependency between packages within this monorepo, you can add the dependency in the dependent package's package.json with a * as the version specification.

• Specifying * instructs Lerna that it should call the build script of the dependency before calling the build script of the dependning application.

Externally

If you would like to establish a dependency between packages within this monorepo and an external client application that consumes these packages,

1. Run npm link at the root of the specific package you are making code changes in.
2. Run npx lerna run build --scope <package> to build that specific package.
3. In the client application, run npm link <package> --force to ensure that the package.json of the client application is updated with a file: link to the dependency. This effectively creates a symlink in the node_modules of the client application to the local dependency.

Having done this setup, this is what the development cycle looks like moving forward:

1. Make code change
2. Rebuild specific package
3. Rebuild client application.