Getting Started With Lerna

Resources

tl;dr

mkdir hello-lerna
cd hello-lerna
yarn init -y

# init lerna with cli tool
npx lerna init

# make a packages directory with each of your packages
mkdir packages

# make a few packages for the example
mkdir packages/package-one
mkdir packages/package-two
mkdir packages/package-three

# yarn init all packages and generate a basic file for each
cd packages/package-one && yarn init -y && touch index.js
cat > index.js << EOT
module.exports = {
  value: 1
}
EOT
cd ../package-two && yarn init -y && touch index.js
cat > index.js << EOT
module.exports = {
  value: 2
}
EOT
cd ../package-three && yarn init -y && touch index.js
cat > index.js << EOT
var one = require('package-one')
var two = require('package-two')
console.log(one + two)
EOT

# head back to the root of the project
cd ../..
copy

Now we update packages/package-three/package.json to include our other two dependencies:

{
  "dependencies": {
    "package-one": "0.1.0",
    "package-two": "0.1.0"
  }
}
copy

If we now run lerna bootstrap we can link up all the packages.

If we now run node ./packages/pacakge-three/index.js we should see 3 in the console!

What is it?

From resource (1):

Lerna is a tool that allows you to maintain multiple npm packages within one repository.

There's a couple of benefits to this kind of approach, the paradigm is called a monorepo, and more can be read about it from the source of babel, and react.

Here's the gist: