PostCSS Config Module JS

PostCSS configuration examples often show common js code with module.exports.

module.exports = {
  plugins: [
    require('autoprefixer')
  ]
}

If your project is a JS module, with "type": "module" in package.json, it will complain that the config file is not a JS module.

To fix it, you can change the file extension to .cjs, meaning it is a common JS script so it won't try to run as a module.

Or you can convert it to module syntax with export default {}.

import autoprefixer from "autoprefixer";

export default {
  plugins: [
    autoprefixer,
  ]
}