creat-react-app构建react项目并配置less，sass等样式

项目构建步骤：

1.cd到你的项目要存放的位置，然后执行以下命令全局安装create-react-app脚手架

npm install -g create-react-app

执行成功结果显示

C:\Users\Saiang>d:
D:\>cd projects
D:\projects>npm install -g create-react-app
C:\Users\Saiang\AppData\Roaming\npm\create-react-app -> C:\Users\Saiang\AppData\Roaming\npm\node_modules\create-react-app\index.js
+ [email protected]
updated 1 package in 7.987s

D:\projects>

2.执行以下命令，初始化你要创建的项目，其中'my-app'为项目名称，可以自己定义，执行成功显示如下：

C:\Users\Saiang>d:

D:\>cd projects

D:\projects>npm install -g create-react-app
C:\Users\Saiang\AppData\Roaming\npm\create-react-app -> C:\Users\Saiang\AppData\Roaming\npm\node_modules\create-react-app\index.js
+ [email protected]
updated 1 package in 7.987s

D:\projects>create-react-app my-app

Creating a new React app in D:\projects\my-app.

Installing packages. This might take a couple of minutes.
Installing react, react-dom, and react-scripts...

yarn add v1.3.2
info No lockfile found.
[1/4] Resolving packages...
warning react-scripts > autoprefixer > [email protected]: Browserslist 2 could fail on reading Browserslist >3.0 config used in other tools.
warning react-scripts > css-loader > cssnano > autoprefixer > [email protected]: Browserslist 2 could fail on reading Browserslist >3.0 config used in other tools.
warning react-scripts > babel-preset-react-app > babel-preset-env > [email protected]: Browserslist 2 could fail on reading Browserslist >3.0 config used in other tools.
warning react-scripts > css-loader > cssnano > postcss-merge-rules > [email protected]: Browserslist 2 could fail on reading Browserslist >3.0 config used in other tools.
warning react-scripts > css-loader > cssnano > postcss-merge-rules > caniuse-api > [email protected]: Browserslist 2 could fail on reading Browserslist >3.0 config used in other tools.
warning react-scripts > jest > jest-cli > istanbul-api > [email protected]: 1.2.0 should have been a major version bump
[2/4] Fetching packages...
info [email protected]: The platform "win32" is incompatible with this module.
info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation.
[3/4] Linking dependencies...
[4/4] Building fresh packages...
success Saved lockfile.
success Saved 943 new dependencies.
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Done in 102.53s.

Success! Created my-app at D:\projects\my-app
Inside that directory, you can run several commands:

  yarn start
    Starts the development server.

  yarn build
    Bundles the app into static files for production.

  yarn test
    Starts the test runner.

  yarn eject
    Removes this tool and copies build dependencies, configuration files
    and scripts into the app directory. If you do this, you can’t go back!

We suggest that you begin by typing:

  cd my-app
  yarn start

Happy hacking!

D:\projects>

3.cd 到新建的项目中去，然后执行npm start启动服务，成功后会自动打开浏览器地址：http://localhost:3000

D:\projects>cd my-app

D:\projects\my-app>npm start

> [email protected] start D:\projects\my-app
> react-scripts start




Starting the development server...
Compiled successfully!

You can now view my-app in the browser.

  Local:            http://localhost:3000/
  On Your Network:  http://192.168.0.106:3000/

Note that the development build is not optimized.
To create a production build, use yarn build.

4.页面效果如下，到这里我们就已经成功的创建了一个react项目了

5.用自己习惯的ide打开项目，查看项目文件夹结构：我们看到项目默认是用的css样式的，也就是说构建工具默认不支持sass,less,等预编译，如果我们相用这些来写样式的话改如何配置呢？

6.修改配置第一步执行以下命令暴露原有的配置：npm run eject,执行成功之后，文件夹会有改动，新增了一个config文件夹和一个script文件夹，接下来我们就可以通过修改这里面的配置来达到目的了

Microsoft Windows [版本 10.0.16299.431]
(c) 2017 Microsoft Corporation。保留所有权利。

D:\projects\my-app>npm run eject

> [email protected] eject D:\projects\my-app
> react-scripts eject

? Are you sure you want to eject? This action is permanent. Yes
Ejecting...

Copying files into D:\projects\my-app
  Adding \config\env.js to the project
  Adding \config\paths.js to the project
  Adding \config\polyfills.js to the project
  Adding \config\webpack.config.dev.js to the project
  Adding \config\webpack.config.prod.js to the project
  Adding \config\webpackDevServer.config.js to the project
  Adding \config\jest\cssTransform.js to the project
  Adding \config\jest\fileTransform.js to the project
  Adding \scripts\build.js to the project
  Adding \scripts\start.js to the project
  Adding \scripts\test.js to the project

Updating the dependencies
  Removing react-scripts from dependencies
  Adding autoprefixer to dependencies
  Adding babel-core to dependencies
  Adding babel-eslint to dependencies
  Adding babel-jest to dependencies
  Adding babel-loader to dependencies
  Adding babel-preset-react-app to dependencies
  Adding babel-runtime to dependencies
  Adding case-sensitive-paths-webpack-plugin to dependencies
  Adding chalk to dependencies
  Adding css-loader to dependencies
  Adding dotenv to dependencies
  Adding dotenv-expand to dependencies
  Adding eslint to dependencies
  Adding eslint-config-react-app to dependencies
  Adding eslint-loader to dependencies
  Adding eslint-plugin-flowtype to dependencies
  Adding eslint-plugin-import to dependencies
  Adding eslint-plugin-jsx-a11y to dependencies
  Adding eslint-plugin-react to dependencies
  Adding extract-text-webpack-plugin to dependencies
  Adding file-loader to dependencies
  Adding fs-extra to dependencies
  Adding html-webpack-plugin to dependencies
  Adding jest to dependencies
  Adding object-assign to dependencies
  Adding postcss-flexbugs-fixes to dependencies
  Adding postcss-loader to dependencies
  Adding promise to dependencies
  Adding raf to dependencies
  Adding react-dev-utils to dependencies
  Adding resolve to dependencies
  Adding style-loader to dependencies
  Adding sw-precache-webpack-plugin to dependencies
  Adding url-loader to dependencies
  Adding webpack to dependencies
  Adding webpack-dev-server to dependencies
  Adding webpack-manifest-plugin to dependencies
  Adding whatwg-fetch to dependencies

Updating the scripts
  Replacing "react-scripts start" with "node scripts/start.js"
  Replacing "react-scripts build" with "node scripts/build.js"
  Replacing "react-scripts test" with "node scripts/test.js"

Configuring package.json
  Adding Jest configuration
  Adding Babel preset
  Adding ESLint configuration

Ejected successfully!

Please consider sharing why you ejected in this survey:
  http://goo.gl/forms/Bi6CZjk1EqsdelXk1


D:\projects\my-app>

 

 

7.如果想用less的话，(这里我就以less为例)，则需要先安装两个插件

D:\projects\my-app>npm install less-loader less --save-dev
npm WARN [email protected] requires a peer of ajv@^6.0.0 but none was installed.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for [email protected]: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})

+ [email protected]
+ [email protected]
added 73 packages and removed 3 packages in 14.567s

D:\projects\my-app>

8.安装成功之后，要一次修改 webpack.config.dev.js 和 webpack.config-prod.js 这两个配置文件

接下来：

注意：webpack.config-prod.js 文件里面执行和上面两步一模一样的操作即可，

最后配置已经修改完了，让我们来把之前的的css文件改造成.less文件看有没有效果，把app.css改成app.less并修改成less样式代码如下，观察页面效果是一模一样的，所以到这一步就已经完全成功了

.App {
  text-align: center;
  .App-header {
    background-color: #222;
    height: 150px;
    padding: 20px;
    color: white;
    .App-logo {
      animation: App-logo-spin infinite 20s linear;
      height: 80px;
    }
    .App-title {
      font-size: 1.5em;
    }
  }
  .App-intro {
    font-size: large;
  }
}

@keyframes App-logo-spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}