responsively-app/browser-extension/webpack.config.js

const path = require('path');
const SizePlugin = require('size-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const WebExtWebpackPlugin = require('@ianwalter/web-ext-webpack-plugin');
const TerserPlugin = require('terser-webpack-plugin');

module.exports = {
	devtool: 'source-map',
	stats: 'errors-only',
	entry: {
		background: './src/background',
		popup: './src/popup',
	},
	output: {
		path: path.join(__dirname, 'dist'),
		filename: '[name].js'
	},
	module: {
    rules: [
      {
        test: /\.js$/,
        include: [
          path.resolve(__dirname, "src")
        ],
        use: {
          loader: 'babel-loader',
          options: {
            presets: [
              ["@babel/preset-env", { modules: false }],
              "@babel/preset-react"
            ],
            plugins: [
              "@babel/plugin-transform-react-constant-elements",
              "@babel/plugin-proposal-object-rest-spread",
              "@babel/plugin-proposal-class-properties",
              "@babel/plugin-transform-runtime",
            ],
          },
        },
			},
			{
        test: /\.(svg|gif|png|jpg)$/,
        use: 'url-loader',
      }
		],
	},
	plugins: [
		new SizePlugin(),
		new CopyWebpackPlugin([
			{
				from: '**/*',
				context: 'public',
			},
			{
				from: 'node_modules/webextension-polyfill/dist/browser-polyfill.min.js'
			}
		]),
		new WebExtWebpackPlugin({ sourceDir: path.join(__dirname, 'dist'), verbose: true }),
	],
	optimization: {
		minimizer: [
			new TerserPlugin({
				terserOptions: {
					mangle: false,
					compress: false,
					output: {
						beautify: true,
						indent_level: 2 // eslint-disable-line camelcase
					}
				}
			})
		]
	}
};