webpack.config.dev.js

const webpack = require('webpack');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');

module.exports = {
  devtool: 'cheap-module-eval-source-map',
  entry: `${__dirname}/app/index.js`,
  output: {
    path: `${__dirname}/public/script/`,
    filename: 'bundle.js',
    chunkFilename: 'chunk/[name].chunk.js',
    publicPath: '/script/',
  },
  module: {
    rules: [{
      test: /\.js$/,
      exclude: /node_modules/,
      loader: 'babel-loader',
    }, {
      test: /\.(png|jpg|gif)$/,
      loader: 'url-loader?limit=40000',
    }, {
      test: /\.css$/,
      use: ExtractTextPlugin.extract({
        fallback: 'style-loader',
        use: 'css-loader',
      }),
    }, {
      test: /\.scss$/,
      use: ExtractTextPlugin.extract({
        fallback: 'style-loader',
        use: ['css-loader', 'sass-loader'],
      }),
    }],
  },
  plugins: [
    new ExtractTextPlugin('../style/style.css', {
      allChunks: true,
    }),
    new webpack.DllReferencePlugin({
      context: __dirname,
      manifest: require('./manifest.json'),
    }),
    new OptimizeCssAssetsPlugin({
      assetNameRegExp: /.css$/g,
      cssProcessor: require('cssnano'),
      cssProcessorOptions: {
        discardComments: {
          removeAll: true,
        },
      },
      canPrint: true,
    }),
  ],
};