block7.js

// Process JS with Babel.
{
  test: /\.(js|jsx)$/,
  include: paths.appSrc,
  loader: require.resolve('babel-loader'),
  options: {
    // This is a feature of `babel-loader` for Webpack (not Babel itself).
    // It enables caching results in ./node_modules/.cache/babel-loader/
    // directory for faster rebuilds.
    cacheDirectory: true,
    plugins: ['react-hot-loader/babel'],
  },
}