当我们create-react-app以后项目里面自带的目录很少，webpack.config.js去哪里了？我怎么配置插件？怎么修改loader？
打开目录进入package.json以后发现scripts里面有
"scripts": {
"start": "react-scripts start",//开启一个微服务
"build": "react-scripts build",//构建项目
"test": "react-scripts test",//测试
"eject": "react-scripts eject"//释放配置
},
npm run start ===npm start--开启一个微服务，在浏览器出现一个http://localhost:3000 的页面。
npm run build以后在目录里面会出现一个新的文件夹build，里面就装载的是webpack打包构建出来的文件
npm run test不用解释
npm run eject 执行这个命令以后会将webpack，babel所有的配置都释放出来，这个命令只能执行一次，当出现eject成功以后，在package.json里面的scripts里面只有三个命令，eject命令消失
"scripts": {
"start": "node scripts/start.js",
"build": "node scripts/build.js",
"test": "node scripts/test.js"
},
并且dependencies里面的依赖也有原来的
"dependencies": {
"@testing-library/jest-dom": "^4.2.4",
"@testing-library/react": "^9.5.0",
"@testing-library/user-event": "^7.2.1",
"react": "^16.13.1",
"react-dom": "^16.13.1",
"react-scripts": "3.4.1"
},
变成了
"dependencies": {
"@babel/core": "7.8.4",
"@svgr/webpack": "4.3.3",
"@testing-library/jest-dom": "^4.2.4",
"@testing-library/react": "^9.5.0",
"@testing-library/user-event": "^7.2.1",
"@typescript-eslint/eslint-plugin": "^2.10.0",
"@typescript-eslint/parser": "^2.10.0",
"antd": "^4.0.3",
"babel-eslint": "10.0.3",
"babel-jest": "^24.9.0",
"babel-loader": "8.0.6",
"babel-plugin-named-asset-import": "^0.3.6",
"babel-preset-react-app": "^9.1.1",
"camelcase": "^5.3.1",
"case-sensitive-paths-webpack-plugin": "2.3.0",
"css-loader": "3.4.2",
"dotenv": "8.2.0",
"dotenv-expand": "5.1.0",
"eslint": "^6.6.0",
"eslint-config-react-app": "^5.2.0",
"eslint-loader": "3.0.3",
"eslint-plugin-flowtype": "4.6.0",
"eslint-plugin-import": "2.20.0",
"eslint-plugin-jsx-a11y": "6.2.3",
"eslint-plugin-react": "7.18.0",
"eslint-plugin-react-hooks": "^1.6.1",
"file-loader": "4.3.0",
"fs-extra": "^8.1.0",
"html-webpack-plugin": "4.0.0-beta.11",
"identity-obj-proxy": "3.0.0",
"immutable": "^4.0.0-rc.12",
"install": "^0.13.0",
"jest": "24.9.0",
"jest-environment-jsdom-fourteen": "1.0.1",
"jest-resolve": "24.9.0",
"jest-watch-typeahead": "0.4.2",
"less": "^3.11.1",
"less-loader": "^5.0.0",
"mini-css-extract-plugin": "0.9.0",
"optimize-css-assets-webpack-plugin": "5.0.3",
"pnp-webpack-plugin": "1.6.0",
"postcss-flexbugs-fixes": "4.1.0",
"postcss-loader": "3.0.0",
"postcss-normalize": "8.0.1",
"postcss-preset-env": "6.7.0",
"postcss-safe-parser": "4.0.1",
"react": "^16.13.0",
"react-app-polyfill": "^1.0.6",
"react-dev-utils": "^10.2.0",
"react-dom": "^16.13.0",
"react-redux": "^7.2.0",
"react-router": "^5.1.2",
"react-router-config": "^5.1.1",
"react-router-dom": "^5.1.2",
"redux": "^4.0.5",
"redux-immutable": "^4.0.0",
"redux-thunk": "^2.3.0",
"resolve": "1.15.0",
"resolve-url-loader": "3.1.1",
"sass-loader": "8.0.2",
"semver": "6.3.0",
"style-loader": "0.23.1",
"styled-components": "^5.0.1",
"swiper": "^5.3.6",
"terser-webpack-plugin": "2.3.4",
"ts-pnp": "1.1.5",
"url-loader": "2.3.0",
"webpack": "4.41.5",
"webpack-dev-server": "3.10.2",
"webpack-manifest-plugin": "2.2.0",
"workbox-webpack-plugin": "4.3.1"
},
同时在目录里面又多出了一个文件夹config，里面装在的就是所有基础配置信息，包裹webpack.config.js文件。
原因从create-react-app说起：安装脚手架以后依赖文件是：react，react-dom，react-scripts。webpack，babel就放在react-scripts里面，如果执行了npm run eject命令以后他就会把配置文件释放出来
如何配置less和ant的按需加载呢？
1.配置less
npm insatll less less-loader -D
编译以后都会变成css，所以用-D开发环境即可。
2.进入config/webpack.config.js文件找到sass的配置文件,我们把自己的配置文件添加在sass后面就好了，并且只需要改改名字，抄上即可
const sassRegex = /\.(scss|sass)$/; // 原有文件
const sassModuleRegex = /\.module\.(scss|sass)$/; // 原有文件
const lessRegex = /\.less$/; // 添加文件
const lessModuleRegex = /\.module\.less$/; // 添加文件
3.找到models下rules里面的sass的配置规则
sass的配置
2.antd按需加载配置
2.1安装babel-plugin-import：npm install babel-plugin-import -D 2.2在webpack.config.js里面配置如下信息：找到module里面关于babel的配置信息 我们将babel-plugin-import 的信息追加在后面即可
总结： 执行create-react-app以后我们应该去观察一下项目，请相信所有存在的东西都是有他的必要的，不要轻易忽略他的存在。常存一颗探索的心灵，对编程，对前端都有很大的帮助。共勉！
