title: Webpack dev server cannot get
body: <p>I' am using Webpack-4. Current behavior is that when webpack-dev-server is running, files under /build not get updated at all and it is showing the file directory.</p>
  
  <p>If I delete the files under /build, webpack-dev-server is giving cannot get/. I assume, It should load them from memory.</p>
  
  <pre><code>const HtmlWebPackPlugin = require("html-webpack-plugin");
  const htmlPlugin = new HtmlWebPackPlugin({
     template: "./src/index.html",
     filename: "./index.html"
  });
  
  const path = require('path');
  
  module.exports = {
  output: {
      filename: 'bundle.js',
      path: path.resolve(__dirname, 'build/'),
  },
  
  module: {
      rules: [{
              test: /\.(js|jsx)$/,
              exclude: /node_modules/,
              use: {
                  loader: "babel-loader",
                  options: {
                      presets: ["env","react"]
                  }
              }
          },
          { 
              test: /\.html$/,
              use: [{
                  loader: "html-loader",
                  options: {
                      minimize: true
                  }
              }]
          }
      ]
  },
  plugins: [
      htmlPlugin
  ],
  devServer: {       
      contentBase: "./build/",
      port: 5555
  }
  }
  </code></pre>