Aliases

Aliases let you install packages with custom names.

Let's assume you use lodash all over your project. There is a bug in lodash that breaks your project. You have a fix but lodash won't merge it. Normally you would either install lodash from your fork directly (as a git-hosted dependency) or publish it with a different name. If you use the second solution you have to replace all the requires in your project with the new dependency name (require('lodash') => require('awesome-lodash')). With aliases, you have a third option.

Publish a new package called awesome-lodash and install it using lodash as its alias:

pnpm add lodash@npm:awesome-lodash

No changes in code are needed. All the requires of lodash will now resolve to awesome-lodash.

Sometimes you'll want to use two different versions of a package in your project. Easy:

pnpm add lodash1@npm:lodash@1
pnpm add lodash2@npm:lodash@2

Now you can require the first version of lodash via require('lodash1') and the second via require('lodash2').

This gets even more powerful when combined with hooks. Maybe you want to replace lodash with awesome-lodash in all the packages in node_modules. You can easily achieve that with the following .pnpmfile.cjs:

function readPackage(pkg) {
  if (pkg.dependencies && pkg.dependencies.lodash) {
    pkg.dependencies.lodash = 'npm:awesome-lodash@^1.0.0'
  }
  return pkg
}

module.exports = {
  hooks: {
    readPackage
  }
}