我正在尝试用我的React项目配置sass。我已经在Webpack.config.dev/prod.js上设置sass停留了几个小时。在线上的许多教程都建议使用rules字段，但找不到它。而且，当我自己添加它时，它也不起作用。

这是我的webpack.config.dev.js

'use strict';

var autoprefixer = require('autoprefixer');
var webpack = require('webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
var CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
var InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
var WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
var getclientEnvironment = require('./env');
var paths = require('./paths');



// Webpack uses `publicPath` to determine where the app is being served from.
// In development,we always serve from the root. This makes config easier.
var publicPath = '/';
// `publicUrl` is just like `publicPath`,but we will provide it to our app
// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
// Omit trailing slash as %PUBLIC_PATH%/xyz looks better than %PUBLIC_PATH%xyz.
var publicUrl = '';
// Get environment variables to inject into our app.
var env = getclientEnvironment(publicUrl);

// This is the development configuration.
// It is focused on developer experience and fast rebuilds.
// The production configuration is different and lives in a separate file.
module.exports = {
  // You may want 'eval' instead if you prefer to see the compiled output in DevTools.
  // See the discussion in https://github.com/facebookincubator/create-react-app/issues/343.
  devtool: 'cheap-module-source-map',// These are the "entry points" to our application.
  // This means they will be the "root" imports that are included in JS bundle.
  // The first two entry points enable "hot" CSS and auto-refreshes for JS.
  entry: [
    // Include an alternative client for Webpackdevserver. A client's job is to
    // connect to Webpackdevserver by a socket and get notified about changes.
    // When you save a file,the client will either apply hot updates (in case
    // of CSS changes),or refresh the page (in case of JS changes). When you
    // make a syntax error,this client will display a syntax error overlay.
    // Note: instead of the default Webpackdevserver client,we use a custom one
    // to bring better experience for Create React App users. You can replace
    // the line below with these two lines if you prefer the stock client:
    // require.resolve('webpack-dev-server/client') + '?/',// require.resolve('webpack/hot/dev-server'),require.resolve('react-dev-utils/webpackHotDevClient'),// We ship a few polyfills by default:
    require.resolve('./polyfills'),// Finally,this is your app's code:
    paths.appIndexJs
    // We include the app code last so that if there is a runtime error during
    // initialization,it doesn't blow up the Webpackdevserver client,and
    // changing JS code would still trigger a refresh.
  ],output: {
    // Next line is not used in dev but Webpackdevserver crashes without it:
    path: paths.appBuild,// Add /* filename */ comments to generated require()s in the output.
    pathinfo: true,// This does not produce a real file. It's just the virtual path that is
    // served by Webpackdevserver in development. This is the JS bundle
    // containing code from all our entry points,and the Webpack runtime.
    filename: 'static/js/bundle.js',// This is the URL that app is served from. We use "/" in development.
    publicPath: publicPath
  },resolve: {
    // This allows you to set a fallback for where Webpack should look for modules.
    // We read `NODE_PATH` environment variable in `paths.js` and pass paths here.
    // We use `fallback` instead of `root` because we want `node_modules` to "win"
    // if there any conflicts. This matches Node resolution mechanism.
    // https://github.com/facebookincubator/create-react-app/issues/253
    fallback: paths.nodePaths,// These are the reasonable defaults supported by the Node ecosystem.
    // We also include JSX as a common component filename extension to support
    // some tools,although we do not recommend using it,see:
    // https://github.com/facebookincubator/create-react-app/issues/290
    extensions: ['.js','.json','.jsx',''],alias: {
      // Support React Native Web
      // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
      'react-native': 'react-native-web'
    }
  },module: {
    // First,run the linter.
    // It's important to do this before Babel processes the JS.
    preLoaders: [
      {
        test: /\.(js|jsx)$/,loader: 'eslint',include: paths.appSrc,}
    ],loaders: [
      // ** ADDING/UPDATING LOADERS **
      // The "url" loader handles all assets unless explicitly excluded.
      // The `exclude` list *must* be updated with every change to loader extensions.
      // When adding a new loader,you must add its `test`
      // as a new entry in the `exclude` list for "url" loader.

      // "url" loader embeds assets smaller than specified size as data URLs to avoid requests.
      // Otherwise,it acts like the "file" loader.
      {
        exclude: [
          /\.html$/,// We have to write /\.(js|jsx)(\?.*)?$/ rather than just /\.(js|jsx)$/
          // because you might change the hot reloading server from the custom one
          // to Webpack's built-in webpack-dev-server/client?/,which would not
          // get properly excluded by /\.(js|jsx)$/ because of the query string.
          // Webpack 2 fixes this,but for now we include this hack.
          // https://github.com/facebookincubator/create-react-app/issues/1713
          /\.(js|jsx)(\?.*)?$/,/\.css$/,/\.json$/,/\.svg$/,/\.scss$/
        ],loader: 'url',query: {
          limit: 10000,name: 'static/media/[name].[hash:8].[ext]'
        }
      },// Process JS with Babel.
      {
        test: /\.(js|jsx)$/,loader: 'babel',query: {

          // This is a feature of `babel-loader` for webpack (not Babel itself).
          // It enables caching results in ./node_modules/.cache/babel-loader/
          // directory for faster rebuilds.
          cacheDirectory: true
        }
      },// "postcss" loader applies autoprefixer to our CSS.
      // "css" loader resolves paths in CSS and adds assets as dependencies.
      // "style" loader turns CSS into JS modules that inject <style> tags.
      // In production,we use a plugin to extract that CSS to a file,but
      // in development "style" loader enables hot editing of CSS.
      {
        test: /\.css$/,loader: 'style!css?importLoaders=1!postcss'
      },// JSON is not enabled by default in Webpack but both Node and Browserify
      // allow it implicitly so we also enable it.
      {
        test: /\.json$/,loader: 'json'
      },// "file" loader for svg
      {
        test: /\.svg$/,loader: 'file',query: {
          name: 'static/media/[name].[hash:8].[ext]'
        }
      },{
        test:/\.scss$/,loaders: [
          'style-loader','css-loader','sass-loader'
        ]
      }
      // ** STOP ** Are you adding a new loader?
      // Remember to add the new extension(s) to the "url" loader exclusion list.
    ]
  },// We use PostCSS for autoprefixing only.
  postcss: function() {
    return [
      autoprefixer({
        browsers: [
          '>1%','last 4 versions','Firefox ESR','not ie < 9',// React doesn't support IE8 anyway
        ]
      }),];
  },plugins: [
    // Makes some environment variables available in index.html.
    // The public URL is available as %PUBLIC_URL% in index.html,e.g.:
    // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
    // In development,this will be an empty string.
    new InterpolateHtmlPlugin(env.raw),// Generates an `index.html` file with the <script> injected.
    new HtmlWebpackPlugin({
      inject: true,template: paths.appHtml,}),// Makes some environment variables available to the JS code,for example:
    // if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
    new webpack.DefinePlugin(env.stringified),// This is necessary to emit hot updates (currently CSS only):
    new webpack.HotModuleReplacementPlugin(),// Watcher doesn't work well if you mistype casing in a path so we use
    // a plugin that prints an error when you attempt to do this.
    // See https://github.com/facebookincubator/create-react-app/issues/240
    new CaseSensitivePathsPlugin(),// If you require a missing module and then `npm install` it,you still have
    // to restart the development server for Webpack to discover it. This plugin
    // makes the discovery automatic so you don't have to restart.
    // See https://github.com/facebookincubator/create-react-app/issues/186
    new WatchMissingNodeModulesPlugin(paths.appNodeModules)
  ],// Some libraries import Node modules but don't use them in the browser.
  // Tell Webpack to provide empty mocks for them so importing them works.
  node: {
    fs: 'empty',net: 'empty',tls: 'empty'
  }
};

当我运行npm run build时，出现编译错误Module parsed failed...index.scss. You may need an appropriate loader to handle this file type。