react create-react-app v5 从零搭建（使用 npm run eject）

前言：

好久没用 create-react-app做项目了，这次为了个h5项目，就几个页面，决定自己搭建一个（ps:mmp 好久没用，搭建的时候遇到一堆问题）。

我之前都是使用 umi 。后台管理系统的项目 使用 antd-pro框架。实际上antd-pro 是基于umi搭建集成的框架。里面封装好了各种东西，开箱即用。

如果不想暴露 eject 可以参考 ：
react create-react-app v5 从零搭建项目 不暴露 eject

我的环境如下：
create-react-app v5

    "axios": "^1.5.0",
    "http-proxy-middleware": "^2.0.6",
    "react": "^18.2.0",
    "react-dom": "^18.2.0",
    "react-router": "^6.16.0",
    "react-router-dom": "^6.16.0",

搭建过程：

一、创建项目：
安装Node 和 npm: Node >= 14.0.0 和 npm >= 5.6

npx install -g create-react-app

npx create-react-app my-app

npx 不是拼写错误 —— 它是 npm 5.2+ 附带的 package 运行工具。

react 官网文档

二、配置各种必备的东西

npm start 运行 看到下图就说明项目创建成功了！

运行 npm run eject 此命令一旦运行不可逆!!!
如果不想 用这种方式可以参考：
react create-react-app v5 从零搭建项目 不运行 eject

配置less:

1.安装 less和less-loader

npm install less less-loader --save-dev

2.找到 config/webpack.config.js 添加less规则代码如下：

const lessRegex = /\.less$/; 
const lessModuleRegex = /\.module\.less$/;

3.搜索oneOf，在oneOf数组中添加以下代码：

//less 配置
            {
              test: lessRegex,
              exclude: lessModuleRegex,
              use: getStyleLoaders(
                  {
                  importLoaders: 2,
                  sourceMap: isEnvProduction
                      ? shouldUseSourceMap
                      : isEnvDevelopment,
                  },
                  "less-loader"
              ),
              sideEffects: true,
          },
          //less 模块化配置
          {
              test: lessModuleRegex,
              use: getStyleLoaders(
                  {
                  importLoaders: 2,
                  sourceMap: isEnvProduction
                      ? shouldUseSourceMap
                      : isEnvDevelopment,
                      modules: {
                          getLocalIdent: getCSSModuleLocalIdent,
                      },
                  },
                  "less-loader"
              ),
          },

要放到 sass-loader下面，位置不对可能不生效

我一开始放到了这里（错误示范）就不生效。

4.重新 npm start(修改 webpack.config.js里的东西 都要重新运行，别忘记保存！！！)
然后 直接 import ‘./App.less’ 或者 模块化引入 import styles from “./index.module.less”(当然 App.less 也要改成 App.module.less)。

看到 和 App.css运行的效果一样则说明配置成功。

配置路由：

1.下载 react-router-dom

npm install react-router-dom

2.App.js 里 写上如下代码：

import React from "react";
import { BrowserRouter, Routes, Route } from "react-router-dom";
import routes from './routes';
const App = () => {
  console.log(routes)
  return (
    <BrowserRouter>
      <Routes>
        {routes.map((route) => (
          <Route key={route.path} path={route.path} element={route.component} />
        ))}
        {/* } />  */}
      </Routes>
    </BrowserRouter>
  );
};

export default App;

遇到 Uncaught TypeError: Cannot read properties of null (reading ‘useRef‘) 报错可以看：
react create-react-app 配置路由报错(Uncaught TypeError: Cannot read properties of null (reading ‘useRef‘))
3.index.js里写上：

import React from 'react';
import ReactDOM from 'react-dom/client';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(
  <React.StrictMode>
    <App />
   </React.StrictMode> 
);

// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();

4.在src下新建一个 routes.js文件 写上：

// 导入你的页面组件  
import Home from './pages'; 
const routes = [
  { path: "/", component: <Home/>}
];

export default routes;

运行看到 Home组件里的东西就说明成功了。之后可以在 scr/router.js里导入其他组件 写上 path和routers就行了。

注意：react-router-dom v6 和v5 api不太一样，比如 v5 把 Route 上是 component v6是element。具体写法 建议参考 你所用的版本 文档！

如果遇到了Uncaught TypeError: Cannot read properties of null (reading ‘useRef‘) 报错，可以看https://blog.csdn.net/weixin_44058725/article/details/133316898

配置axios：

1.安装 axios

cnpm install axios --save

2.src/utils 新建一个 request.js文件(没有utils就新建一个目录然后再建一个request.js)
3.request代码如下：
这个是最简单的配置了，你可以根据自己的需求配置 请求拦截里的东西。

import axios from 'axios'

 // axios的配置文件, 可以在这里去区分开发环境和生产环境等全局一些配置
 const devBaseUrl = 'http://api.k780.com/'
 const proBaseUrl = 'http://xxxxx.com/'
 
 // process.env返回的是一个包含用户的环境信息,它可以去区分是开发环境还是生产环境
 export const BASE_URL =  process.env.NODE_ENV === 'development' ? devBaseUrl : proBaseUrl
 export const TIMEOUT = 5000

var request = axios.create({
    baseURL:BASE_URL,//基准地址
    timeout:TIMEOUT
})
//拦截请求
request.interceptors.request.use((config)=>{
    return config
})
//拦截响应
request.interceptors.response.use((response)=>{
    return response
},function (error){
    //对响应的错误做点什么
    return Promise.reject(error);
}
)
 
export default request;

配置Proxy代理：

使用 http-proxy-middleware
1.安装http-proxy-middleware

npm install http-proxy-middleware --save

2.根目录新建一个setupProxy.js
代码大致如下：
然后 请求接口时以/api/xx就会自动走代理。

const { createProxyMiddleware } = require('http-proxy-middleware');

module.exports = function(app) {
    app.use(
      '/api',
      createProxyMiddleware({
        target: 'http://localhost:8000',
        changeOrigin: true,
        // pathRewrite: {  
        //     '^/api': '/',  
        //   },  
      })
    );
  };

配置 px2rem：

具体请看：react create-react-app v5配置 px2rem （暴露 eject方式）

配置别名 src可以用 @ ：

1.在 config/webpack.config.js里搜索 alias 然后 加上

"@": paths.appSrc,

2.在 App.js里测试一下，引入 app的样式文件，我是 App.less。
import ‘@/App.less’;

3.重新运行 npm start 如果，样式确实生效了就说明，配置对了。

配置按需加载：

注意：antd-mobile无需配置手动按需加载
antd-mobile 按需加载

其实 antd 高版本也自带按需加载 可以不用配置（下面的代码只是个 演示，你如果有其他 ui库 或者 插件需要按需加载可以按照下面的步骤来）：

antd 官方链接 按需加载

如果你有其他插件需要配置可以参考这个步骤来：
1.找到 config/webpack.config.js 然后 搜索 oneOf 在下面加一个配置：
其实和配置less差不多。

{   //配置按需加载 
            test: /\.less$/,  
            use: [  
              'style-loader',  
              'css-loader',  
              'less-loader',  
              {  
                loader: 'babel-loader',  
                options: {  
                  plugins: [  
                    [  
                      'import',  
                      {  
                        libraryName: 'antd',  
                        libraryDirectory: 'es',  
                        style: true, // 如果你使用的是 less，则设置为 true  
                      },  
                    ],  
                  ],  
                },  
              },  
            ],  
            include: /node_modules/,  
          },

我的 webpack.config.js完整的配置：

你可以参考对比：

'use strict';

const fs = require('fs');
const path = require('path');
const webpack = require('webpack');
const resolve = require('resolve');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
const InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin');
const TerserPlugin = require('terser-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');
const { WebpackManifestPlugin } = require('webpack-manifest-plugin');
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
const WorkboxWebpackPlugin = require('workbox-webpack-plugin');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
const ESLintPlugin = require('eslint-webpack-plugin');
const paths = require('./paths');
const modules = require('./modules');
const getClientEnvironment = require('./env');
const ModuleNotFoundPlugin = require('react-dev-utils/ModuleNotFoundPlugin');
const ForkTsCheckerWebpackPlugin =
  process.env.TSC_COMPILE_ON_ERROR === 'true'
    ? require('react-dev-utils/ForkTsCheckerWarningWebpackPlugin')
    : require('react-dev-utils/ForkTsCheckerWebpackPlugin');
const ReactRefreshWebpackPlugin = require('@pmmmwh/react-refresh-webpack-plugin');

const createEnvironmentHash = require('./webpack/persistentCache/createEnvironmentHash');

//px2rem的配置
const px2rem = require("postcss-plugin-px2rem");
const px2remOpts = {
	rootValue: 37.5, //这个值定义了1rem应该等于多少像素。在这里，1rem等于37.5
	exclude: /(node_module)/, //这是一个正则表达式，用于指定哪些文件应该被排除在转换之外。在这里，所有在'node_module'目录下的文件都将被排除。
	// mediaQuery: false, //这个选项表示是否应该在媒体查询中转换px单位。在这里，它被设置为false，意味着媒体查询中的px单位将不会被转换
	// minPixelValue: 3, //这个选项表示应该转换的最小px值。在这里，只有px值大于或等于3的才会被转换
};


// Source maps are resource heavy and can cause out of memory issue for large source files.
const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';

const reactRefreshRuntimeEntry = require.resolve('react-refresh/runtime');
const reactRefreshWebpackPluginRuntimeEntry = require.resolve(
  '@pmmmwh/react-refresh-webpack-plugin'
);
const babelRuntimeEntry = require.resolve('babel-preset-react-app');
const babelRuntimeEntryHelpers = require.resolve(
  '@babel/runtime/helpers/esm/assertThisInitialized',
  { paths: [babelRuntimeEntry] }
);
const babelRuntimeRegenerator = require.resolve('@babel/runtime/regenerator', {
  paths: [babelRuntimeEntry],
});

// Some apps do not need the benefits of saving a web request, so not inlining the chunk
// makes for a smoother build process.
const shouldInlineRuntimeChunk = process.env.INLINE_RUNTIME_CHUNK !== 'false';

const emitErrorsAsWarnings = process.env.ESLINT_NO_DEV_ERRORS === 'true';
const disableESLintPlugin = process.env.DISABLE_ESLINT_PLUGIN === 'true';

const imageInlineSizeLimit = parseInt(
  process.env.IMAGE_INLINE_SIZE_LIMIT || '10000'
);

// Check if TypeScript is setup
const useTypeScript = fs.existsSync(paths.appTsConfig);

// Check if Tailwind config exists
const useTailwind = fs.existsSync(
  path.join(paths.appPath, 'tailwind.config.js')
);

// Get the path to the uncompiled service worker (if it exists).
const swSrc = paths.swSrc;

// style files regexes
const cssRegex = /\.css$/;
const cssModuleRegex = /\.module\.css$/;
const sassRegex = /\.(scss|sass)$/;
const sassModuleRegex = /\.module\.(scss|sass)$/;
const lessRegex = /\.less$/; 
const lessModuleRegex = /\.module\.less$/;

const hasJsxRuntime = (() => {
  if (process.env.DISABLE_NEW_JSX_TRANSFORM === 'true') {
    return false;
  }

  try {
    require.resolve('react/jsx-runtime');
    return true;
  } catch (e) {
    return false;
  }
})();

// This is the production and development configuration.
// It is focused on developer experience, fast rebuilds, and a minimal bundle.
module.exports = function (webpackEnv) {
  const isEnvDevelopment = webpackEnv === 'development';
  const isEnvProduction = webpackEnv === 'production';

  // Variable used for enabling profiling in Production
  // passed into alias object. Uses a flag if passed into the build command
  const isEnvProductionProfile =
    isEnvProduction && process.argv.includes('--profile');

  // We will provide `paths.publicUrlOrPath` to our app
  // as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
  // Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
  // Get environment variables to inject into our app.
  const env = getClientEnvironment(paths.publicUrlOrPath.slice(0, -1));

  const shouldUseReactRefresh = env.raw.FAST_REFRESH;

  // common function to get style loaders
  const getStyleLoaders = (cssOptions, preProcessor) => {
    const loaders = [
      isEnvDevelopment && require.resolve('style-loader'),
      isEnvProduction && {
        loader: MiniCssExtractPlugin.loader,
        // css is located in `static/css`, use '../../' to locate index.html folder
        // in production `paths.publicUrlOrPath` can be a relative path
        options: paths.publicUrlOrPath.startsWith('.')
          ? { publicPath: '../../' }
          : {},
      },
      {
        loader: require.resolve('css-loader'),
        options: cssOptions,
      },
      {
        // Options for PostCSS as we reference these options twice
        // Adds vendor prefixing based on your specified browser support in
        // package.json
        loader: require.resolve('postcss-loader'),
        options: {
          postcssOptions: {
            // Necessary for external CSS imports to work
            // https://github.com/facebook/create-react-app/issues/2677
            ident: 'postcss',
            config: false,
            plugins: !useTailwind
              ? [
                  'postcss-flexbugs-fixes',
                  [
                    'postcss-preset-env',
                    {
                      autoprefixer: {
                        flexbox: 'no-2009',
                      },
                      stage: 3,
                    },
                  ],
                  [
                    px2rem(px2remOpts)
                  ],
                  // Adds PostCSS Normalize as the reset css with default options,
                  // so that it honors browserslist config in package.json
                  // which in turn let's users customize the target behavior as per their needs.
                  'postcss-normalize',
                ]
              : [
                  'tailwindcss',
                  'postcss-flexbugs-fixes',
                  [
                    'postcss-preset-env',
                    {
                      autoprefixer: {
                        flexbox: 'no-2009',
                      },
                      stage: 3,
                    },
                  ],
                ],
          },
          sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
        }
      }       
    ].filter(Boolean);
    if (preProcessor) {
      loaders.push(
        {
          loader: require.resolve('resolve-url-loader'),
          options: {
            sourceMap: isEnvProduction ? shouldUseSourceMap : isEnvDevelopment,
            root: paths.appSrc,
          },
        },
        {
          loader: require.resolve(preProcessor),
          options: {
            sourceMap: true,
          },
        }
      );
    }
    return loaders;
  };

  return {
    target: ['browserslist'],
    // Webpack noise constrained to errors and warnings
    stats: 'errors-warnings',
    mode: isEnvProduction ? 'production' : isEnvDevelopment && 'development',
    // Stop compilation early in production
    bail: isEnvProduction,
    devtool: isEnvProduction
      ? shouldUseSourceMap
        ? 'source-map'
        : false
      : isEnvDevelopment && '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.
    entry: paths.appIndexJs,
    output: {
      // The build folder.
      path: paths.appBuild,
      // Add /* filename */ comments to generated require()s in the output.
      pathinfo: isEnvDevelopment,
      // There will be one main bundle, and one file per asynchronous chunk.
      // In development, it does not produce real files.
      filename: isEnvProduction
        ? 'static/js/[name].[contenthash:8].js'
        : isEnvDevelopment && 'static/js/bundle.js',
      // There are also additional JS chunk files if you use code splitting.
      chunkFilename: isEnvProduction
        ? 'static/js/[name].[contenthash:8].chunk.js'
        : isEnvDevelopment && 'static/js/[name].chunk.js',
      assetModuleFilename: 'static/media/[name].[hash][ext]',
      // webpack uses `publicPath` to determine where the app is being served from.
      // It requires a trailing slash, or the file assets will get an incorrect path.
      // We inferred the "public path" (such as / or /my-project) from homepage.
      publicPath: paths.publicUrlOrPath,
      // Point sourcemap entries to original disk location (format as URL on Windows)
      devtoolModuleFilenameTemplate: isEnvProduction
        ? info =>
            path
              .relative(paths.appSrc, info.absoluteResourcePath)
              .replace(/\\/g, '/')
        : isEnvDevelopment &&
          (info => path.resolve(info.absoluteResourcePath).replace(/\\/g, '/')),
    },
    cache: {
      type: 'filesystem',
      version: createEnvironmentHash(env.raw),
      cacheDirectory: paths.appWebpackCache,
      store: 'pack',
      buildDependencies: {
        defaultWebpack: ['webpack/lib/'],
        config: [__filename],
        tsconfig: [paths.appTsConfig, paths.appJsConfig].filter(f =>
          fs.existsSync(f)
        ),
      },
    },
    infrastructureLogging: {
      level: 'none',
    },
    optimization: {
      minimize: isEnvProduction,
      minimizer: [
        // This is only used in production mode
        new TerserPlugin({
          terserOptions: {
            parse: {
              // We want terser to parse ecma 8 code. However, we don't want it
              // to apply any minification steps that turns valid ecma 5 code
              // into invalid ecma 5 code. This is why the 'compress' and 'output'
              // sections only apply transformations that are ecma 5 safe
              // https://github.com/facebook/create-react-app/pull/4234
              ecma: 8,
            },
            compress: {
              ecma: 5,
              warnings: false,
              // Disabled because of an issue with Uglify breaking seemingly valid code:
              // https://github.com/facebook/create-react-app/issues/2376
              // Pending further investigation:
              // https://github.com/mishoo/UglifyJS2/issues/2011
              comparisons: false,
              // Disabled because of an issue with Terser breaking valid code:
              // https://github.com/facebook/create-react-app/issues/5250
              // Pending further investigation:
              // https://github.com/terser-js/terser/issues/120
              inline: 2,
            },
            mangle: {
              safari10: true,
            },
            // Added for profiling in devtools
            keep_classnames: isEnvProductionProfile,
            keep_fnames: isEnvProductionProfile,
            output: {
              ecma: 5,
              comments: false,
              // Turned on because emoji and regex is not minified properly using default
              // https://github.com/facebook/create-react-app/issues/2488
              ascii_only: true,
            },
          },
        }),
        // This is only used in production mode
        new CssMinimizerPlugin(),
      ],
    },
    resolve: {
      // This allows you to set a fallback for where webpack should look for modules.
      // We placed these paths second because we want `node_modules` to "win"
      // if there are any conflicts. This matches Node resolution mechanism.
      // https://github.com/facebook/create-react-app/issues/253
      modules: ['node_modules', paths.appNodeModules].concat(
        modules.additionalModulePaths || []
      ),
      // 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/facebook/create-react-app/issues/290
      // `web` extension prefixes have been added for better support
      // for React Native Web.
      extensions: paths.moduleFileExtensions
        .map(ext => `.${ext}`)
        .filter(ext => useTypeScript || !ext.includes('ts')),
      alias: {
        // Support React Native Web
        // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
        'react-native': 'react-native-web',
        // Allows for better profiling with ReactDevTools
        ...(isEnvProductionProfile && {
          'react-dom$': 'react-dom/profiling',
          'scheduler/tracing': 'scheduler/tracing-profiling',
        }),
        "@": paths.appSrc,
        ...(modules.webpackAliases || {}),
      },
      plugins: [
        // Prevents users from importing files from outside of src/ (or node_modules/).
        // This often causes confusion because we only process files within src/ with babel.
        // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
        // please link the files into your node_modules/ and let module-resolution kick in.
        // Make sure your source files are compiled, as they will not be processed in any way.
        new ModuleScopePlugin(paths.appSrc, [
          paths.appPackageJson,
          reactRefreshRuntimeEntry,
          reactRefreshWebpackPluginRuntimeEntry,
          babelRuntimeEntry,
          babelRuntimeEntryHelpers,
          babelRuntimeRegenerator,
        ]),
      ],
    },
    module: {
      strictExportPresence: true,
      rules: [
        // Handle node_modules packages that contain sourcemaps
        shouldUseSourceMap && {
          enforce: 'pre',
          exclude: /@babel(?:\/|\\{1,2})runtime/,
          test: /\.(js|mjs|jsx|ts|tsx|css)$/,
          loader: require.resolve('source-map-loader'),
        },
        {
          // "oneOf" will traverse all following loaders until one will
          // match the requirements. When no loader matches it will fall
          // back to the "file" loader at the end of the loader list.
          oneOf: [
            // TODO: Merge this config once `image/avif` is in the mime-db
            // https://github.com/jshttp/mime-db
            {
              test: [/\.avif$/],
              type: 'asset',
              mimetype: 'image/avif',
              parser: {
                dataUrlCondition: {
                  maxSize: imageInlineSizeLimit,
                },
              },
            },
            // "url" loader works like "file" loader except that it embeds assets
            // smaller than specified limit in bytes as data URLs to avoid requests.
            // A missing `test` is equivalent to a match.
            {
              test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
              type: 'asset',
              parser: {
                dataUrlCondition: {
                  maxSize: imageInlineSizeLimit,
                },
              },
            },
            {
              test: /\.svg$/,
              use: [
                {
                  loader: require.resolve('@svgr/webpack'),
                  options: {
                    prettier: false,
                    svgo: false,
                    svgoConfig: {
                      plugins: [{ removeViewBox: false }],
                    },
                    titleProp: true,
                    ref: true,
                  },
                },
                {
                  loader: require.resolve('file-loader'),
                  options: {
                    name: 'static/media/[name].[hash].[ext]',
                  },
                },
              ],
              issuer: {
                and: [/\.(ts|tsx|js|jsx|md|mdx)$/],
              },
            },
            // Process application JS with Babel.
            // The preset includes JSX, Flow, TypeScript, and some ESnext features.
            {
              test: /\.(js|mjs|jsx|ts|tsx)$/,
              include: paths.appSrc,
              loader: require.resolve('babel-loader'),
              options: {
                customize: require.resolve(
                  'babel-preset-react-app/webpack-overrides'
                ),
                presets: [
                  [
                    require.resolve('babel-preset-react-app'),
                    {
                      runtime: hasJsxRuntime ? 'automatic' : 'classic',
                    },
                  ],
                ],
                
                plugins: [
                  isEnvDevelopment &&
                    shouldUseReactRefresh &&
                    require.resolve('react-refresh/babel'),
                ].filter(Boolean),
                // 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,
                // See #6846 for context on why cacheCompression is disabled
                cacheCompression: false,
                compact: isEnvProduction,
              },
            },
            // Process any JS outside of the app with Babel.
            // Unlike the application JS, we only compile the standard ES features.
            {
              test: /\.(js|mjs)$/,
              exclude: /@babel(?:\/|\\{1,2})runtime/,
              loader: require.resolve('babel-loader'),
              options: {
                babelrc: false,
                configFile: false,
                compact: false,
                presets: [
                  [
                    require.resolve('babel-preset-react-app/dependencies'),
                    { helpers: true },
                  ],
                ],
                cacheDirectory: true,
                // See #6846 for context on why cacheCompression is disabled
                cacheCompression: false,
                
                // Babel sourcemaps are needed for debugging into node_modules
                // code.  Without the options below, debuggers like VSCode
                // show incorrect code and set breakpoints on the wrong lines.
                sourceMaps: shouldUseSourceMap,
                inputSourceMap: shouldUseSourceMap,
              },
            },
            // "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