zoro-cli/lib/plugins/config-webpack/template/script/webpack.plugin.js

https://github.com/vuejs/vue-cli

const fs = require('fs')
const path = require('path')
const { importFrom } = require('zoro-cli-util/import')

exports.forEachPlugin = (category, cb) => {
  const pluginDir = path.join(__dirname, `plugin/${category}`)
  if (fs.existsSync(pluginDir)) {
    const idToPlugin = name => ({
      id: name.replace(/^\.\//, 'built-in:'),
      dir: pluginDir,
      apply: importFrom(path.join(pluginDir, name), './index'),
    })
    fs.readdirSync(pluginDir)
      .filter(name => name.charAt(0) !== '.')
      .map(idToPlugin)
      .forEach(({ apply }) => {
        if (typeof apply === 'function') {
          cb(apply)
        }
      })
  }
}