webpack.config.js

const path = require( 'path' );
const TerserPlugin = require( 'terser-webpack-plugin' );

const isProduction = process.env.NODE_ENV === 'production';

module.exports = {
	mode: isProduction ? 'production' : 'development',

	devtool: isProduction ? undefined : 'eval-source-map',

	stats: 'errors-only',

	// https://webpack.js.org/configuration/optimization/#optimization-runtimechunk
	optimization: {
		minimizer: [
			new TerserPlugin( {
				parallel: true,
				extractComments: false,
				terserOptions: {
					output: {
						comments: false,
					},
					compress: {
						passes: 2,
					},
				},
			} ),
		],
	},

	// https://webpack.js.org/configuration/entry-context/#context
	context: path.resolve( __dirname, 'js/src' ),

	// https://webpack.js.org/configuration/entry-context/#entry
	entry: {
		digest: './digest.js',
	},

	// https://webpack.js.org/configuration/output/
	output: {
		path: path.resolve( __dirname, 'js' ),
		filename: '[name].js',
	},

	// https://github.com/babel/babel-loader#usage
	module: {
		rules: [
			{
				test: /\.js$/,
				exclude: /node_modules/,
				use: 'babel-loader',
			},
		],
	},
};