How to configure webpack dev server with react router dom v4? : <p>This is the code of my webpack configuration: </p>

<pre><code>const compiler = webpack({
  entry: ['whatwg-fetch', path.resolve(__dirname, 'js', 'app.js')], 
  module: {
    loaders: [
      {
        exclude: /node_modules/, 
        test: /\.js$/, 
        loader: 'babel',
      },
    ],
  },
  output: {filename: 'app.js', path: '/'}, 
});

const app = new WebpackDevServer(compiler, {
  contentBase: '/public/', 
  proxy: {'/graphql': `http://localhost:${GRAPHQL_PORT}`},
  publicPath: '/js/',
  stats: {colors: true}, 
});

app.use('/', express.static(path.resolve(__dirname, 'public')));
</code></pre>

<p>Works fine, the app runs on localhost:3000/index.html but when I try to implement React Router dom v4. It doesn't work. This is the code:</p>

<pre><code>const About = () =&gt; &lt;div&gt; &lt;h1&gt;About&lt;/h1&gt; &lt;/div&gt;

ReactDOM.render(
   &lt;BrowserRouter&gt;
      &lt;div&gt;
      &lt;Route exact path='/' component={App}/&gt;
      &lt;Route  path='/about' component={About}/&gt;
      &lt;/div&gt;
    &lt;/BrowserRouter&gt;,
  mountNode
);
</code></pre>

<p>This is the result on localhost:3000/ <a href="https://i.stack.imgur.com/SFFGk.png" rel="noreferrer"><img src="https://i.stack.imgur.com/SFFGk.png" alt="build.min.js"></a>
And on localhost:3000/about. I get an error: Cannot GET /about . Not what I'm expecting, why would this not render?  <h1>About</h1>  </p>
