webpack.config.js

const { NODE_ENV } = process.env;
import path from 'path';

const isDevelopment = NODE_ENV !== 'production';
const sourceMap = isDevelopment;

module.exports = {
	mode: NODE_ENV === 'production' ? NODE_ENV : 'development',
	// the place webpack will start when building your bundles
	entry: {
		main: [
			'@shopify/polaris/styles.css',
			'./client/index.js',
		],
	},
	// sets up rules for any special importers
	module: {
		rules: [
			{
				test: /\.(js|jsx)$/,
				exclude: /node_modules/,
				use: ['babel-loader'],
			},
			{
				test: /\.css$/,
				include: path.resolve(__dirname, './node_modules/@shopify/polaris'),
				use: ['style-loader', 'css-loader' ],
			},
		],
	},
	// file extensions for webpack to look at
	resolve: {
		extensions: ['*', '.js', '.jsx'],
	},
	// where webpack will output your finished bundle
	output: {
		path: __dirname + '/dist',
		publicPath: '/',
		filename: 'bundle.js',
	},
};