index.js

/**
 * UglifyJS webpack block.
 *
 * @see https://github.com/webpack-contrib/uglifyjs-webpack-plugin
 */

const webpackMerge = require('webpack-merge')
const UglifyJSPlugin = require('uglifyjs-webpack-plugin')

module.exports = uglify

/**
 * @param {object} [options] UglifyJS options
 * @return {Function}
 */
function uglify(options = {}) {
  options = webpackMerge(
    {
      parallel: true,
      cache: true,
      uglifyOptions: {
        compress: {
          warnings: false
        }
      }
    },
    options
  )

  const postHook = (context, util) => {
    const plugin = new UglifyJSPlugin(options)
    return util.merge({
      optimization: {
        minimizer: [plugin]
      }
    })
  }

  return Object.assign(() => prevConfig => prevConfig, { post: postHook })
}