How to install npm package in Lerna + Yarn Workspaces repo?

Question

If I want to add dependency to a package, do I need to cd into that directory and run yarn add <package>? Or, is there a command I can run in root directory possibly with a flag like --workspace=<workspace-name>?

Answer 1

You don't need to cd into the package directory and run yarn add <package>. You can use lerna add command with --scope filter option at the root path of your multi-package repository.

Add a single dependency to matched packages

For example, add chalk dependency to packages/pkg-a:

 [main] ⚡  npx lerna add chalk --scope pkg-a
lerna notice cli v3.22.1
lerna notice filter including "pkg-a"
lerna info filter [ 'pkg-a' ]
lerna info Adding chalk in 1 package
lerna info bootstrap root only
npm WARN @octokit/plugin-request-log@1.0.3 requires a peer of @octokit/core@>=3 but none is installed. You must install peer dependencies yourself.

added 6 packages from 3 contributors and audited 1319 packages in 4.811s
found 0 vulnerabilities

After installing, it will add chalk to the dependencies field of packages/pkg-a/package.json file

{
  "name": "pkg-a",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node app.js",
    "test": "jest --config jest.config.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "chalk": "^4.1.0",
    "express": "^4.17.1"
  }
}

lerna version:

[main] ⚡  npx lerna -v     
3.22.1