webpack.config.js

const path = require('path');
const webpack = require('webpack');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const MiniCssExtract = new MiniCssExtractPlugin({
	filename: 'styles.css'
});

process.env.NODE_ENV = process.env.NODE_ENV || 'development';

if (process.env.NODE_ENV === 'test') {
	require('dotenv').config({ path: '.env.test' });
}
else if (process.env.NODE_ENV === 'development') {
	require('dotenv').config({ path: '.env.development' });
}
//process.env.NODE_ENV

module.exports = (env) => {
	const isProduction = env === 'production';
	return {
		entry: ['babel-polyfill', './src/app.js'],
		output: {
			path: path.join(__dirname, 'public', 'dist'),
			filename: 'bundle.js'
		},
		plugins: [MiniCssExtract, new webpack.DefinePlugin({
			'process.env.FIREBASE_API_KEY': JSON.stringify(process.env.FIREBASE_API_KEY),
			'process.env.FIREBASE_AUTH_DOMAIN': JSON.stringify(process.env.FIREBASE_AUTH_DOMAIN),
			'process.env.FIREBASE_DATABASE_URL': JSON.stringify(process.env.FIREBASE_DATABASE_URL),
			'process.env.FIREBASE_PROJECT_ID': JSON.stringify(process.env.FIREBASE_PROJECT_ID),
			'process.env.FIREBASE_STORAGE_BUCKET': JSON.stringify(process.env.FIREBASE_STORAGE_BUCKET),
			'process.env.FIREBASE_MESSAGE_SENDER_ID': JSON.stringify(process.env.FIREBASE_MESSAGE_SENDER_ID),
			'process.env.FIREBASE_APP_ID': JSON.stringify(process.env.FIREBASE_APP_ID),
			'process.env.FIREBASE_MEASUREMENT_ID': JSON.stringify(process.env.FIREBASE_MEASUREMENT_ID)
		})
		],
		module: {
			rules: [
				{
					loader: 'babel-loader',
					test: /\.js$/,
					exclude: /node_modules/
				},
				{
					test: /\.s?css$/,
					use: [
						MiniCssExtractPlugin.loader,
						{
							loader: 'css-loader',
							options: {
								sourceMap: true
							}
						},

						{
							loader: 'sass-loader',
							options: {
								sourceMap: true
							}
						}
					]
				}
			]
		},
		devtool: isProduction ? 'source-map' : 'inline-source-map',
		devServer: {
			contentBase: path.join(__dirname, 'public'),
			historyApiFallback: true,
			publicPath: '/dist/'
		}
	};
};