webpack.config.js

const HtmlWebpackPlugin = require('html-webpack-plugin');
const autoprefixer = require('autoprefixer');

const config = {
  entry: './src/index.js',
  output: {
    filename: '[name].js',
    path: `${__dirname}/dist`,
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
        },
      },
      {
        test: /\.css$/,
        use: [
          'style-loader',
          'css-loader',
          {
            loader: 'postcss-loader',
            options: {
              ident: 'postcss',
              plugins: () => [
                autoprefixer(),
              ],
            },
          },
        ],
      },
    ],
  },
  resolve: {
    extensions: ['.js', '.jsx'],
  },
};

module.exports = (env, argv) => {
  if (argv.mode === 'development') {
    config.devtool = 'source-map';
    config.entry = './example/index.js';
    config.plugins = [
      new HtmlWebpackPlugin({
        template: './example/index.html',
      }),
    ];
  }

  return config;
};