wordpress-develop/tools/webpack/shared.js

/**
 * External dependencies
 */
const TerserPlugin = require( 'terser-webpack-plugin' );
const postcss = require( 'postcss' );
const { join } = require( 'path' );

const baseDir = join( __dirname, '../../' );

const baseConfig = ( env ) => {
	const mode = env.environment;

	const config = {
		target: 'browserslist',
		mode,
		optimization: {
			moduleIds: mode === 'production' ? 'deterministic' : 'named',
			minimizer: [
				new TerserPlugin( {
					extractComments: false,
				} ),
			]
		},
		module: {
			rules: [
				{
					test: /\.js$/,
					use: [ 'source-map-loader' ],
					enforce: 'pre',
				},
			],
		},
		resolve: {
			modules: [
				baseDir,
				'node_modules',
			],
			alias: {
				'lodash-es': 'lodash',
			},
		},
		stats: 'errors-only',
		watch: env.watch,
	};

	if ( mode === 'development' && env.buildTarget === 'build/' ) {
		config.mode = 'production';
		config.optimization = {
			minimize: false,
			moduleIds: 'deterministic',
		};
	} else if ( mode !== 'production' ) {
		config.devtool = process.env.SOURCEMAP || 'source-map';
	}

	return config;
};

const stylesTransform = ( mode ) => ( content ) => {
	if ( mode === 'production' ) {
		return postcss( [
			require( 'cssnano' )( {
				preset: 'default',
			} ),
		] )
			.process( content, { from: 'src/app.css', to: 'dest/app.css' } )
			.then( ( result ) => result.css );
	}
	return content;
};

module.exports = {
	baseDir,
	baseConfig,
	stylesTransform,
};