Understanding the Difference Between `pnpm i` and `pnpm add`: A Guide for Efficient Dependency Management

26 min read

As modern development projects grow in complexity, dependency management tools play a crucial role in streamlining workflows. pnpm, known for its efficient disk space usage and speed, is a popular alternative to traditional tools like npm and yarn. However, understanding the difference between pnpm i and pnpm add can help developers manage dependencies more effectively. In this post, we'll break down what each command does, their use cases, and best practices.

1. What is pnpm i?

The command pnpm i is a shorthand for pnpm install. When executed without specifying any package, it installs all dependencies listed in the project’s pnpm-lock.yaml or package.json file. This is particularly useful when setting up a project for the first time or synchronizing dependencies after a branch switch or pull.

When to Use pnpm i:

  • Setting Up a New Project: If you've cloned a repository and need to install all the listed dependencies, pnpm i is the way to go.
  • Updating Existing Dependencies: After switching branches or pulling the latest changes, you might need to synchronize the dependencies listed in pnpm-lock.yaml.
  • Compatibility with Traditional Install Commands: Similar to running npm install or yarn install, pnpm i will install all dependencies and devDependencies listed in the manifest files.

Example Usage:

pnpm i

This command looks for pnpm-lock.yaml or package.json in the root directory, installs the packages specified, and doesn’t alter the project’s dependency list.

2. What is pnpm add?

pnpm add is specifically designed for adding new dependencies to the project. It updates package.json by default, so any dependency added using pnpm add will also be listed under the relevant dependency field.

Key Differences Between pnpm add and pnpm i:

  • Adding New Dependencies: pnpm add package-name adds a new dependency to the project, which will be recorded in package.json.
  • Control Over Dependency Type: With pnpm add, you can easily specify whether a dependency should be installed as a dependency, devDependency, or optionalDependency by adding flags like -D for dev dependencies.

Example Usage:

pnpm add lodash

This command adds lodash to your project, and it will appear in the dependencies section of package.json.

To install a development dependency, you would use:

pnpm add typescript -D

This command adds typescript as a development dependency, placing it in the devDependencies section of package.json.

3. Summary: Choosing Between pnpm i and pnpm add

Command Purpose Common Use Cases
pnpm i Install all existing dependencies Initial project setup, post-branch switch
pnpm add Add a new dependency Add a library or development tool, update package.json

In summary:

  • Use pnpm i to install dependencies defined in pnpm-lock.yaml or package.json without altering your dependency list.
  • Use pnpm add when adding a new package to your project or updating package.json.

Conclusion

While pnpm i and pnpm add may seem similar, understanding their distinctions helps in managing dependencies efficiently. pnpm i shines when synchronizing dependencies already defined in the project, while pnpm add is ideal for adding new libraries or tools. By applying these commands effectively, developers can streamline their project setup and maintenance processes with pnpm.