package.json scripts that work with npm and yarn?

Question

I am using npm as a build tool and so in my package.json, and some of my scripts depend on other scripts:

{
  "test": "npm run lint && mocha"
}

This hardcodes the npm package manager into package.json. How can make this approach to expressing dependencies work with both npm and yarn?

Answer 1

The $npm_execpath environment variable refers to the build tool, so just replace npm with the $npm_execpath:

{
  "test": "$npm_execpath run lint && mocha"
}

Both npm test and yarn test will work, and will use the appropriate build tool.

Answer 2

While mjs' answer is great, there's also a small package that is purported to work on all environments including Windows: https://www.npmjs.com/package/yarpm

To use in a project, run yarn add yarpm --dev / npm i -D yarpm and then just use yarpm in your scripts like this:

{
  "test": "yarpm run lint && mocha"
}

As the package README notes, you just need to make sure your commands would be suitable for passing through to either yarn or npm: you cannot use arguments/flags that only work on one package manager.