pnpm

pnpm is a package manager for Node.js that stands for “performant npm.” It is designed to be faster and more disk space-efficient than NPM and Yarn. Its key innovation is the way it structures the node_modules directory and shares dependencies between projects.

Info

pnpm’s main advantage comes from its use of a content-addressable file system to store all downloaded package files directly on disk. This means packages are downloaded only once and then linked to from individual projects.

Core Philosophy

• Efficiency: Reduce disk space usage and speed up installation by avoiding package duplication.
• Strictness: Create a non-flat node_modules directory to prevent packages from accessing dependencies they don’t explicitly declare in their package.json.
• Determinism: Ensure that an installation is reliable and reproducible across different machines.

How It Works

Instead of the flat node_modules directory created by NPM, pnpm uses symbolic links to create a nested dependency tree. The actual package files are stored in a global, content-addressable store (~/.pnpm-store).

This approach has two major benefits:

1. Disk Space Savings: If multiple projects use the same version of a package, they all link to the same set of files in the global store. There is no duplication.
2. Faster Installations: If a package is already in the store, pnpm can link it almost instantly without re-downloading.

Key Features

• Content-Addressable Store: A single source of truth for all packages on a machine.
• Non-Flat node_modules: Prevents packages from accessing undeclared dependencies, which can hide bugs.
• Monorepo Support: Excellent built-in support for managing multi-package repositories (monorepos).
• Compatibility: Fully compatible with the NPM registry and package.json format.

Common Commands

pnpm commands are very similar to NPM’s.

# Install all dependencies for a project
pnpm install
 
# Add a new package
pnpm add <package_name>
 
# Add a new development dependency
pnpm add -D <package_name>
 
# Remove a package
pnpm remove <package_name>
 
# Run a script
pnpm run <script_name>

pnpm offers a compelling alternative to traditional package managers by solving common problems related to performance and disk space. Its strictness also encourages better dependency management practices, making it a popular choice for modern JavaScript projects.