react 从零开始搭建开发环境

1.创建 package.json 项目

npm init

2.安装 webpack, 并且设置为项目依赖：

npm install webpack --save-dev

当然你必须之前已经在 -g 下安装了 webpack

3.创建一个 webpack.config.js 文件，这个文件是 webpack 工作的参考。

我们对着 https://webpack.js.org/configuration/ 这个文档来创建 webpack.config.js 文件。

webpack.config.js 文件：

const path = require('path');

module.exports = {
  entry: "./app/entry", // string | object | array
  // Here the application starts executing
  // and webpack starts bundling

  output: {
    // options related to how webpack emits results

    path: path.resolve(__dirname, "dist"), // string
    // the target directory for all output files
    // must be an absolute path (use the Node.js path module)

    filename: "bundle.js", // string
    // the filename template for entry chunks

    publicPath: "/assets/", // string
    // the url to the output directory resolved relative to the HTML page

    library: "MyLibrary", // string,
    // the name of the exported library

    libraryTarget: "umd", // universal module definition
    // the type of the exported library

    /* Advanced output configuration (click to show) */
  },

  module: {
    // configuration regarding modules

    rules: [
      // rules for modules (configure loaders, parser options, etc.)

      {
        test: /\.jsx?$/,
        include: [
          path.resolve(__dirname, "app")
        ],
        exclude: [
          path.resolve(__dirname, "app/demo-files")
        ],
        // these are matching conditions, each accepting a regular expression or string
        // test and include have the same behavior, both must be matched
        // exclude must not be matched (takes preferrence over test and include)
        // Best practices:
        // - Use RegExp only in test and for filename matching
        // - Use arrays of absolute paths in include and exclude
        // - Try to avoid exclude and prefer include

        issuer: { test, include, exclude },
        // conditions for the issuer (the origin of the import)

        enforce: "pre",
        enforce: "post",
        // flags to apply these rules, even if they are overridden (advanced option)

        loader: "babel-loader",
        // the loader which should be applied, it'll be resolved relative to the context
        // -loader suffix is no longer optional in webpack2 for clarity reasons
        // see webpack 1 upgrade guide

        options: {
          presets: ["es2015"]
        },
        // options for the loader
      },

      {
        test: /\.html$/,

        use: [
          // apply multiple loaders and options
          "htmllint-loader",
          {
            loader: "html-loader",
            options: {
              /* ... */
            }
          }
        ]
      },

      { oneOf: [ /* rules */ ] },
      // only use one of these nested rules

      { rules: [ /* rules */ ] },
      // use all of these nested rules (combine with conditions to be useful)

      { resource: { and: [ /* conditions */ ] } },
      // matches only if all conditions are matched

      { resource: { or: [ /* conditions */ ] } },
      { resource: [ /* conditions */ ] },
      // matches if any condition is matched (default for arrays)

      { resource: { not: /* condition */ } }
      // matches if the condition is not matched
    ],

    /* Advanced module configuration (click to show) */
  },

  resolve: {
    // options for resolving module requests
    // (does not apply to resolving to loaders)

    modules: [
      "node_modules",
      path.resolve(__dirname, "app")
    ],
    // directories where to look for modules

    extensions: [".js", ".json", ".jsx", ".css"],
    // extensions that are used

    alias: {
      // a list of module name aliases

      "module": "new-module",
      // alias "module" -> "new-module" and "module/path/file" -> "new-module/path/file"

      "only-module$": "new-module",
      // alias "only-module" -> "new-module", but not "only-module/path/file" -> "new-module/path/file"

      "module": path.resolve(__dirname, "app/third/module.js"),
      // alias "module" -> "./app/third/module.js" and "module/file" results in error
      // modules aliases are imported relative to the current context
    },
    /* alternative alias syntax (click to show) */

    /* Advanced resolve configuration (click to show) */
  },

  performance: {
    hints: "warning", // enum
    maxAssetSize: 200000, // int (in bytes),
    maxEntrypointSize: 400000, // int (in bytes)
    assetFilter: function(assetFilename) {
      // Function predicate that provides asset filenames
      return assetFilename.endsWith('.css') || assetFilename.endsWith('.js');
    }
  },

  devtool: "source-map", // enum
  // enhance debugging by adding meta info for the browser devtools
  // source-map most detailed at the expense of build speed.

  context: __dirname, // string (absolute path!)
  // the home directory for webpack
  // the entry and module.rules.loader option
  //   is resolved relative to this directory

  target: "web", // enum
  // the environment in which the bundle should run
  // changes chunk loading behavior and available modules

  externals: ["react", /^@angular\//],
  // Don't follow/bundle these modules, but request them at runtime from the environment

  stats: "errors-only",
  // lets you precisely control what bundle information gets displayed

  devServer: {
    proxy: { // proxy URLs to backend development server
      '/api': 'http://localhost:3000'
    },
    contentBase: path.join(__dirname, 'public'), // boolean | string | array, static file location
    compress: true, // enable gzip compression
    historyApiFallback: true, // true for index.html upon 404, object for multiple paths
    hot: true, // hot module replacement. Depends on HotModuleReplacementPlugin
    https: false, // true for self-signed, object for cert authority
    noInfo: true, // only errors & warns on hot reload
    // ...
  },

  plugins: [
    // ...
  ],
  // list of additional plugins

  /* Advanced configuration (click to show) */
}

实例：

const path = require('path');

module.exports = {
  // 入口文件
  entry: "./app/main.js",
  // 出口文件
  output: {
    path: path.resolve(__dirname, "dist"), // string
    filename: "all.js" // string
  }
}

至此，我们的 webpack 就已经可以进行标准的 CMD 模块化开发了。

4.我们引入 babel-loader 翻译 ES6：

npm install --save-dev babel-loader
npm install --save-dev babel-core
npm install --save-dev babel-preset-es2015

我们参考 https://github.com/babel/babel-loader 改变 webpack.config.js 文件：

const path = require('path');

module.exports = {
  // 入口文件
  entry: "./app/main.js",
  // 出口文件
  output: {
    path: path.resolve(__dirname, "dist"), // string
    filename: "all.js" // string
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['es2015']
          }
        }
      }
    ]
  }
}

友情提醒：webpack1 和 2 在配置上差别最大的就是 loader 的书写方法。

module  -->  rules  -->  test / exclude / use 属性，这是标准的 webpack2 的写法。

5.此时运行

webpack

命令，将自动的使用 CMD 构建 app 文件夹中的 main.js 文件，并且使用 babel 翻译。

6.下面继续配置 react：

npm install --save-dev react
npm install --save-dev react-dom

配置 解析 JSX 语法：

npm install --save-dev babel-preset-react

至此，我们已经配置完毕 react 起步的所有的依赖，我们目前的 package.json 文件：

{
  "name": "01_helloworld",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "babel-core": "^6.26.0",
    "babel-loader": "^7.1.2",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "react": "^16.2.0",
    "react-dom": "^16.2.0",
    "webpack": "^2.4.1"
  }
}

.