title: extract CSS from js component with webpack
body: <p>I am using React and splitting CSS with each Component.
  and I want to extract CSS from these files.</p>
  
  <pre><code>// ComponentA.js
  import "./ComponentA.css"
  export default class ComponentA extends React.Component {
      ...
  }
  
  // ComponentB.js
  import "./ComponentB.css"
  export default class ComponentB extends React.Component {
      ...
  }
  
  // index.js
  import ComponentA from "./ComponentA"
  import ComponentB from "./ComponentB"
  class App extends React.Component {
      render() {
          return (
              &lt;div&gt;
                  &lt;ComponentA /&gt;
                  &lt;ComponentB /&gt;
              &lt;/div&gt;
          )
      }
  }
  </code></pre>
  
  <p>in this case, how can i extract and bundle <code>ComponentA.css</code> and <code>ComponentB.css</code> </p>
  
  <p>without transpile whole JS sources?</p>