webpack.config.js

// entry -> output
const path = require('path');
const webpack = require('webpack');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
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 = 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' });
}

module.exports = (env) => {
  const isProduction = env === 'production';
  const CSSExtract = new ExtractTextPlugin('styles.css');

  return {
    entry: ['babel-polyfill', './src/app.js'], // Babel polyfill for not supported browsers
    output: {
      path: path.join(__dirname, 'public', 'dist'),
      filename: 'bundle.js',
    },
    module: {
      rules: [
        {
          loader: 'babel-loader',
          test: /\.js$/,
          exclude: /node_modules/,
        },
        {
          test: /\.s?css$/,
          use: CSSExtract.extract({
            use: [
              {
                loader: 'css-loader',
                options: {
                  sourceMap: true,
                },
              },
              {
                loader: 'sass-loader',
                options: {
                  sourceMap: true,
                },
              },
            ],
          }),
        },
      ],
    },
    plugins: [CSSExtract, 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_MESSAGING_SENDER_ID': JSON.stringify(process.env.FIREBASE_MESSAGING_SENDER_ID),
    })],
    devtool: isProduction ? 'source-map' : 'cheap-module-source-map',
    devServer: {
      contentBase: path.join(__dirname, 'public'), // where find the bundles styles and js
      historyApiFallback: true, // tell em the webserver to return to home if a 404 ocurr
      publicPath: '/dist/',
    },
  };
};