webpack.config.js

var path = require('path');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const devMode = process.env.NODE_ENV !== 'production'

module.exports = {
  mode : devMode ? 'development' : 'production',
  entry: [
    './src/index.js'
  ],
  output: {
    path: path.resolve(__dirname, "dist"),
    filename: "bundle.js",
    publicPath: "/dist"
  },
  module: {
    rules: [
      {
        exclude: /node_modules/,
        test: /\.js$/,
        use: [
          {
            loader: 'babel-loader',
            options: {
              presets: ['react', 'es2015', 'stage-1']
            }
          }
        ]
      },
      {
        test: /\.s?[ac]ss$/,
        use: [
            MiniCssExtractPlugin.loader,
            { loader: 'css-loader', options: { url: false, sourceMap: true } },
            { loader: 'sass-loader', options: { sourceMap: true } }
        ],
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
        filename: "style.css"
    })
  ],
  devtool: 'source-map',
  resolve: {
    extensions: ['.js', '.jsx']
  },
  devServer: {
    historyApiFallback: true,
    contentBase: './'
  }
};