webpack.config.js

const path = require('path');
const defaultConfig = require('@wordpress/scripts/config/webpack.config');
const WooCommerceDependencyExtractionWebpackPlugin = require('@woocommerce/dependency-extraction-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

// Remove SASS rule from the default config so we can define our own.
const defaultRules = defaultConfig.module.rules.filter((rule) => {
	return String(rule.test) !== String(/\.(sc|sa)ss$/);
});

module.exports = {
	...defaultConfig,
	entry: {
		index: path.resolve(process.cwd(), 'src', 'index.js' ),
		'checkout-block-frontend':
			path.resolve(
				process.cwd(),
				'src',
				'frontend.js'
			),
	},
	module: {
		...defaultConfig.module,
		rules: [
			...defaultRules,
			{
				test: /\.(sc|sa)ss$/,
				exclude: /node_modules/,
				use: [
					MiniCssExtractPlugin.loader,
					{ loader: 'css-loader', options: { importLoaders: 1 } },
					{
						loader: 'sass-loader',
						options: {
							sassOptions: {
								includePaths: ['src/css'],
							},
							additionalData: (content, loaderContext) => {
								const { resourcePath, rootContext } =
									loaderContext;
								const relativePath = path.relative(
									rootContext,
									resourcePath
								);

								if (relativePath.startsWith('src/css/')) {
									return content;
								}

								// Add code here to prepend to all .scss/.sass files.
								//return '@import "_colors"; ' + content;
							},
						},
					},
				],
			},
		],
	},
	plugins: [
		...defaultConfig.plugins.filter(
			(plugin) =>
				plugin.constructor.name !== 'DependencyExtractionWebpackPlugin'
		),
		new WooCommerceDependencyExtractionWebpackPlugin(),
		new MiniCssExtractPlugin({
			filename: `[name].css`,
		}),
	],
};