npmの平坦なツリー構造​

npm maintains aflattened dependency tree as of version 3. This leads to lessdisk space bloat, with a messynode_modules directory as a side effect.

On the other hand, pnpm managesnode_modules by using hard linking andsymbolic linking to a global on-disk content-addressable store. This lets you get the benefits of far less disk space usage, while also keeping yournode_modules clean. There is documentation on thestore layout if you wishto learn more.

The good thing about pnpm's propernode_modules structure is that it"helps to avoid silly bugs" by making it impossible to use modules that are notspecified in the project'spackage.json.

インストール​

pnpm does not allow installation of packages without saving them topackage.json. If no parameters are passed topnpm add, packages are saved asregular dependencies. Like with npm,--save-dev and--save-optional can beused 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'swhy pnpm's implementation of theprune command does not allow you to specifypackages 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 thefile: prefix and point to a directory inthe 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 calledfoo (<root>/foo) that hasbar@file:../bar as a dependency, pnpm won't perform installation for<root>/bar when you runpnpm install onfoo.

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