Currently, pnpm list and pnpm why can only search for dependencies by name (and optionally version). For example:

pnpm why minimist

prints the chain of dependencies to any installed instance of minimist:

verdaccio 5.20.1
├─┬ handlebars 4.7.7
│ └── minimist 1.2.8
└─┬ mv 2.1.1
  └─┬ mkdirp 0.5.6
    └── minimist 1.2.8

What if we want to search by other properties of a dependency, not just its name? For instance, find all packages that have react@17 in their peer dependencies?

This is currently not possible. You could try to analyze the lockfile manually but it gets really hard with bigger projects. Also, not all information is present in the lockfile.

My suggested solution for this is introducing "finder functions". Finder functions can be declared via .pnpmfile.cjs and invoked using the --find-by=<function name> flag, when using pnpm list or pnpm why.

Let's say we want to find any dependencies that have react 17 in peer dependencies. We can add this finder to our .pnpmfile.cjs:

module.exports = {
  finders: {
    react17: (ctx) => {
      return ctx.readManifest().peerDependencies?.react === '^17.0.0'
    }
  }
}

Now we can use this finder function by running:

pnpm why --find-by=react17

pnpm will find all dependencies that have this react in peer dependencies and print their exact locations in the dependency graph.

@apollo/client 4.0.4
├── @graphql-typed-document-node/core 3.2.0
└── graphql-tag 2.12.6

It is also possible to print out some additional information in the output by returning a string from the finder. For example, with the following funder:

module.exports = {
  finders: {
    react17: (ctx) => {
      const manifest = ctx.readManifest()
      if (manifest.peerDependencies?.react === '^17.0.0') {
        return `license: ${manifest.license}`
      }
      return false
    }
  }
}

Every matched package will also print out the license from it's package.json:

@apollo/client 4.0.4
├── @graphql-typed-document-node/core 3.2.0
│   license: MIT
└── graphql-tag 2.12.6
    license: MIT