Pnpm Monorepo Mastery
Introduction to pnpm
A Better Package Manager
If you've worked with JavaScript, you've used a package manager. Tools like npm and Yarn are essential for installing and managing project dependencies—the libraries and frameworks your code relies on. But as projects grow, so does the node_modules folder, often ballooning to consume gigabytes of disk space.
This happens because for every project on your machine, npm and Yarn create a separate node_modules folder and download fresh copies of every single dependency. If you have ten projects that all use React, you have ten copies of React on your hard drive. This is not only inefficient in terms of space but also slows down installation times.
pnpm, which stands for "performant npm," is a package manager that solves these problems with a clever approach to storing and linking dependencies.
Instead of duplicating files, pnpm maintains a single, global store of packages on your machine. When you install a dependency in a project, pnpm doesn't copy it. Instead, it creates a hard link from your project's node_modules folder to the package in the global store. A hard link is like a shortcut, but your system sees it as the actual file. This means you only ever have one copy of a specific package version, no matter how many projects use it.
By using hard links and a global store, PNPM avoids the common issue of redundant copies of dependencies across projects.
This approach has two major benefits:
- Disk Space Efficiency: You can save gigabytes of disk space, especially if you work on multiple projects that share common dependencies.
- Faster Installations: Since packages are downloaded only once, subsequent installations in other projects are significantly faster. pnpm simply links to the existing files instead of re-downloading them.
Getting Started with pnpm
Switching to pnpm is straightforward. First, you need to install it globally using npm (which typically comes with Node.js).
npm install -g pnpm
Once pnpm is installed, you can use it just like you would npm or Yarn. The commands are very similar, making the transition easy. Here are the basic commands you'll use most often:
# Install dependencies listed in package.json
pnpm install
# Add a new package as a dependency
pnpm add express
# Add a new package as a dev dependency
pnpm add -D jest
# Remove a package
pnpm remove lodash
# Run a script from package.json
pnpm run dev
That’s it! The next time you start a new project or clone an existing one, try running pnpm install instead of npm install. You'll likely notice an immediate improvement in speed and a much smaller footprint on your disk.
What is the primary problem with traditional package managers like npm and Yarn that pnpm is designed to solve?
How does pnpm manage dependencies to save disk space?
By understanding how pnpm manages dependencies differently, you can make your development workflow faster and more efficient.