React 在 IE 11 下無法顯示

錯誤訊息

1	typeof Symbol&&Symbol.for&&Symbol.for("react.element")\|\|60103

會出現這個問題的原因是因為 react 和 react-dom　所使用的 polyfill　的版本不同
需要在 webpack.config => entry　中的第一行加入所要用的 polyfill　版本

entry: [
 'babel-polyfill', // Load this first
 'react-hot-loader/patch', // This package already requires/loads react (but not react-dom). It must be loaded after babel-polyfill to ensure both react and react-dom use the same Symbol.
 'react', // Include this to enforce order
 'react-dom', // Include this to enforce order
 './index.js' // Path to your app's entry file
]

or somthing like this

entry: [
      require.resolve('react-app-polyfill/ie11'),
      isEnvDevelopment &&
      require.resolve('react-dev-utils/webpackHotDevClient'),
      paths.appIndexJs,
],