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pnpm – A better package manager for Node.js

Ankur Mursalin
4 min read

pnpm

We will talk about pnpm, but first let’s have a brief introduction on package manager

Node.js is a popular choice for developers which allows using JavaScript on both client and server side. Having a big community, node.Js provides numerous public and private packages to integrate into projects. To manage these projects, we have package manager. npm is the standard package manager for node.js

How npm works

  1. On a freshly installed device, npm reads package.json file and starts checking the defined version on npm registry
  2. On matching the version, it firsts download the package in global cache directory of the device
  3. Later copies the package on the node_modules directory of the project specific directory
  4. While running the project, packages in the project specific directory is used
  5. The global cache directory helps npm to find the specific version of package when that version is required again

It’s kind of a good approach. However, there are some cons to this approach

  • Redundant use of device space – We are pointing inefficient use of non-volatile memory (SSD, HDD). It is common that one can have multiple similar project. In that case, most of the packages (and their version) will be same. However, for each one of them, a package will be copied to multiple project specific directory. Those node_modules directories will gradually take up device space which u need to store other resources. U may all have seen this meme 😀
big-node-modules
long-npm-install
  • Long installation time – U may not worry about disk space. But lengthy installation time will scare you. For a relatively simple project, required packages can be large. npm install requires a copy of the package twice. First in global cache directory and later in project specific directory. Copying this every time for every new project will surely kill your time

Better solution

You need to reduce your disk space and installation time. So that, u can focus on development. Now pnpm comes into the picture. The way pnpm works is simple but brilliant.

  1. pnpm download packages from npm registry similar to npm
  2. It stores packages in global cache directory same as npm
  3. Now the magic happens. Instead of copying the packages to project specific directory one by one according to package.json file, it hard links the package to node_modules of project specific directory.
  4. It seems copying, but it is not. As it just links (similar to file/folder shortcut) the package path from global cache directory to project specific directory without copying the whole file. Which saves both installation time and disk space.

Using pnpm in projects

  1. Install pnpm. U may install stand alone script install pnpm globally using npm
  2. With node & npm, It is common to use nvm (node version manager) for different version of node.Js. Remember that, for each version of node, u need to install pnpm globally
  3. Ensure your pnpm executable path is in your global bash PATH. You can add it in your .bashrc or .zshrc file in following way:
    export PNPM_HOME="/Users/ankur/Library/pnpm" export PATH="$PNPM_HOME:$PATH"
  4. pnpm has a rich list of CLI commands for installation, update, run script. Common commands are:
CommandMeaning
pnpm add saxSave to dependencies
pnpm add -D saxSave to devDependencies
pnpm add sax@3.0.0Specify version 3.0.0
pnpm iInstall package from package.json
pnpm rm saxRemove package from package.json
pnpm run <command-name>Run command from package.json
pnpm --filter <package_selector> <command>Filtering allows you to restrict commands to specific subsets of packages.
  1. U can also create multiple workspaces inside your project and handle all the packages from from your root directory using pnpm. It is specially helpful for monorepo. To create workspace, just create a new pnpm-workspace.yaml. In that file you can define your workspaces. U can also use glob pattern. For example: packages: - "packages/*" Now in the scripts section of package.json filter the workspaces "w:server": "pnpm --filter server", "w:client": "pnpm --filter client", Then u can easily run workspace specific command. Something like this pnpm w:server build
  2. You can easily use pnpm in docker
  3. pnpm can easily be used in various continuous integration systems.

Bonus 😀

U can easily debug your server side using vscode with pnpm. U just need to add configuration in your .vscode/launch.json file

{
  "name": "Launch server via pnpm",
  "type": "node",
  "request": "launch",
  "cwd": "${workspaceFolder}",
  "runtimeVersion": "18.11.0",
  "runtimeExecutable": "pnpm",
  "runtimeArgs": ["w:server start"]
}

End:

That’s all!

We hope you’ve found the article useful. You should try pnpm if you haven’t already. Feel free to share your thoughts in the comments below.

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Node.js Quick Hack

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