Why Doesn’t Yarn Create a node_modules Directory?

If you’ve recently run yarn install in a new project, you might be surprised to find that Yarn didn’t generate a node_modules directory. Instead, you’ll notice a .pnp.cjs file and a .yarn directory in your project.

Don’t worry, this is the expected behavior! Yarn has introduced a new package management strategy called Plug’n’Play (PnP) in version 1.12, which eliminates the need for node_modules.

In this guide, we’ll explore:

• Why Yarn no longer creates a node_modules directory
• What the .pnp.cjs file is
• The benefits of using .pnp.cjs over node_modules
• How to enable node_modules if you need it for compatibility issues

Let’s dive in 🤿

📹Prefer a video tutorial instead? Treat your ears to my soothing voice ( ͡° ͜ʖ ͡°)

What is Plug’n’Play?

Yarn’s Plug’n’Play is a modern dependency management approach that replaces the traditional node_modules directory with a more efficient mechanism. Instead of copying dependencies into the project directory, Yarn stores package metadata inside the .pnp.cjs file and keeps the actual dependencies in a global cache.

Key benefits of Plug’n’Play:

• Since dependencies aren’t copied into every project, installations are much quicker.
• Multiple projects can share the same globally cached dependencies, avoiding unnecessary duplication.
• The .pnp.cjs file acts as a dependency map, helping Yarn resolve package locations efficiently without the nested complexity of node_modules.
• By using a virtual filesystem, Yarn provides packages without physically placing them inside the project folder.

Overall, PnP optimizes dependency management, making it both faster and more disk space-efficient.

Restoring the node_modules Directory

While Plug’n’Play offers significant benefits, some projects may encounter compatibility issues with dependencies that rely on the traditional node_modules structure. If you run into such issues, you can configure Yarn to revert to the old behavior.

To instruct Yarn to create a node_modules directory, run the following command:

yarn config set nodeLinker node-modules

If the above command doesn’t work as expected, you can manually create the .yarnrc.yml file at the root of your project and add the following setting:

nodeLinker: node-modules

Conclusion

Yarn’s Plug’n’Play is a powerful alternative to traditional package management, offering improved speed, reduced disk usage, and better dependency resolution. However, in cases where compatibility issues arise, you can easily switch back to using node_modules.

If you’d like to learn more about Yarn’s Plug’n’Play, check out the official Yarn documentation:

• Plug’n’Play Overview
• Plug’n’Play Specification

Happy coding 💜

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