Can you pass JS functions into the package as configuration?

[steveworkman]

What problem does this feature solve?

I'm creating a standardised babel config in a preset. This config requires that different configuration is used depending on the process.env options, in particular when Jest is running in test mode.

  api.extendPackage({
    babel: {
      ignore:  process.env === "test" ? ["core-js/*"] : []
    }
  });

This results in

module.exports = {
  presets: [
    '@vue/app'
  ],
  ignore: []
}

What does the proposed API look like?

I'm not sure. The generator script is evaluating the code when it is running, so I guess it would need to be a method similar to that but that takes a string to be evaluated.

[haoqunjiang]

See https://github.com/vuejs/vue-cli/blob/dev/packages/%40vue/cli-plugin-eslint/eslintOptions.js

[steveworkman]

That's a lovely bit of black magic right there. It works, and it'd be great to see that as utility as part of the API. Would you be open to a PR for this?

In case this source changes, the code is this:

// __expression is a special flag that allows us to customize stringification
// output when extracting configs into standalone files
function makeJSOnlyValue (str) {
  const fn = () => {}
  fn.__expression = str
  return fn
}

[haoqunjiang]

Yeah, PR is welcome 😀