pnpmとnpmの比較

npmの平坦なツリー構造

npm maintains a flattened dependency tree as of version 3. This leads to less disk space bloat, with a messy node_modules directory as a side effect.

On the other hand, pnpm manages node_modules by using hard linking and symbolic linking to a global on-disk content-addressable store. This lets you get the benefits of far less disk space usage, while also keeping your node_modules clean. There is documentation on the store layout if you wish to learn more.

The good thing about pnpm's proper node_modules structure is that it "helps to avoid silly bugs" by making it impossible to use modules that are not specified in the project's package.json.

インストール

pnpm does not allow installation of packages without saving them to package.json. If no parameters are passed to pnpm add, packages are saved as regular dependencies. Like with npm, --save-dev and --save-optional can be used to install packages as dev or optional dependencies.

結果として、依存関係を削除して、孤立したパッケージだけを残したりしない限り、pnpmを使っていれば無関係なパッケージをプロジェクトに残してしまうことは無くなるでしょう。 That's why pnpm's implementation of the prune command does not allow you to specify packages to prune - it ALWAYS removes all extraneous and orphaned packages.

ディレクトリに対する依存関係

Directory dependencies start with the file: prefix and point to a directory in the filesystem. npmと同様に、pnpmはそれらの依存関係に対するシンボリックリンクを作成します。 ただしnpmと違って、pnpmはファイル依存関係をインストールしません。

This means that if you have a package called foo (<root>/foo) that has bar@file:../bar as a dependency, pnpm won't perform installation for <root>/bar when you run pnpm install on foo.

If you need to run installations in several packages at the same time, for instance in the case of a monorepo, you should look at the documentation for pnpm -r.