Introduction

npm (Node Package Manager) and pnpm (Performant NPM) are both essential tools for managing JavaScript dependencies in projects. While they serve the same fundamental purpose, they differ significantly in how they handle package installation, dependency resolution, and disk space management. Understanding these differences can help you choose the right tool for your specific needs.

npm (Node Package Manager)

npm is the default package manager that comes bundled with Node.js. It has been widely adopted across the JavaScript ecosystem for its familiarity and robust feature set.

• Installation Method: npm installs packages by placing each dependency in its own node_modules folder within the project's directory structure. This approach can lead to duplicated packages across different projects.

• Performance and Disk Usage: npm can be slower and consume more disk space, especially with large projects and complex dependency trees.

• Dependency Resolution: npm installs packages with a nested dependency structure, potentially resulting in larger node_modules directories and longer installation times.

• Lockfile: npm uses a package-lock.json file to lock the versions of installed dependencies, ensuring consistent installations across different environments.

pnpm (Performant NPM)

pnpm is an alternative package manager designed to address the shortcomings of npm, focusing on efficiency and speed.

• Efficiency: pnpm uses a content-addressable storage mechanism to store all package files in a centralized location (~/.pnpm-store). This approach eliminates duplicate packages and reduces disk space usage.

• Installation Method: Instead of duplicating packages, pnpm creates symlinks to a shared node_modules directory, pointing to the packages stored in ~/.pnpm-store. This results in faster installation times and efficient disk space utilization.

• Dependency Resolution: pnpm installs dependencies in a flat directory structure, similar to Yarn, which helps avoid issues related to deeply nested node_modules structures.

• Lockfile: Similar to npm’s package-lock.json, pnpm uses a pnpm-lock.yaml file to lock dependency versions, ensuring consistent installations.

Comparison of Dependency Structures

npm Dependency Structure

Project Root
│
├── node_modules/
│   ├── lodash/
│   │   └── node_modules/
│   │       └── nested-dependency/
│   └── another-package/
│       └── node_modules/
│           └── shared-dependency/
│
└── package.json

pnpm Dependency Structure

Project Root
│
├── node_modules/
│   ├── lodash -> ~/.pnpm-store/lodash@4.17.20 (symlink)
│   └── another-package -> ~/.pnpm-store/another-package@1.2.3 (symlink)
│
└── package.json

~/.pnpm-store/
├── lodash@4.17.20/
└── another-package@1.2.3/

Managing Different Package Versions

In scenarios where different projects require different versions of the same package (e.g., lodash), pnpm efficiently manages versioning:

• Centralized Storage: pnpm stores each package version separately in ~/.pnpm-store, ensuring that multiple versions can coexist without duplication.

• Symlinks: When a project installs a specific package version, pnpm creates a symlink in the project's node_modules directory, pointing to the correct version in ~/.pnpm-store.

Example Scenario

Centralized Storage (~/.pnpm-store)

.pnpm-store/
├── lodash@1.1/
│   └── ... (files for lodash 1.1)
├── lodash@1.2/
│   └── ... (files for lodash 1.2)
└── ... (other packages)

Projects Using Different Versions

• Project A (using lodash@1.1):

  Project A Root
  ├── node_modules/
  │   └── lodash -> ~/.pnpm-store/lodash@1.1 (symlink)
  └── package.json

• Project B (using lodash@1.2):

  Project B Root
  ├── node_modules/
  │   └── lodash -> ~/.pnpm-store/lodash@1.2 (symlink)
  └── package.json

Where Does pnpm Fetch Packages From?

pnpm fetches packages from the same registry as npm, typically the public npm registry (https://registry.npmjs.org). By default, pnpm uses this registry for package downloads, ensuring compatibility and availability.

Conclusion: Choosing Between npm and pnpm

The choice between npm and pnpm depends on your project’s specific requirements and preferences:

npm

• Pros: Widely used, familiar, and compatible with various tools and services.
• Cons: Slower installation times, larger disk space usage, and potential for nested dependency issues.

pnpm

• Pros: Faster installations, efficient disk space usage, and reduced dependency conflicts.
• Cons: Learning curve for teams unfamiliar with its approach, and potential compatibility issues with some tools.

Recommendation

• Use npm if your team is already familiar with it, or if compatibility with existing tools and services is crucial.
• Use pnpm for new projects or large-scale applications where performance, disk space efficiency, and dependency management are critical.

By understanding these differences, you can make an informed decision on whether npm or pnpm is the best fit for your JavaScript project.