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Webpack

Webpack 是一个现代 JavaScript 应用程序的静态模块打包工具。它会递归地构建一个依赖关系图，其中包含应用程序需要的每个模块，然后将这些模块打包成一个或多个 bundle。

1. 基础配置​

1.1 安装​

# 安装 webpack
npm install webpack webpack-cli --save-dev

# 开发服务器
npm install webpack-dev-server --save-dev

# 常用 loader
npm install babel-loader style-loader css-loader file-loader url-loader --save-dev

# 常用插件
npm install html-webpack-plugin mini-css-extract-plugin clean-webpack-plugin --save-dev

1.2 基础配置文件​

// webpack.config.js
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  // 入口
  entry: './src/index.js',
  
  // 输出
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: '[name].[contenthash].js',
    clean: true
  },
  
  // 模块处理
  module: {
    rules: [
      // JavaScript
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader'
        }
      },
      // CSS
      {
        test: /\.css$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader'
        ]
      },
      // 图片
      {
        test: /\.(png|svg|jpg|jpeg|gif)$/i,
        type: 'asset/resource'
      }
    ]
  },
  
  // 插件
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/index.html'
    }),
    new MiniCssExtractPlugin({
      filename: '[name].[contenthash].css'
    })
  ]
};

2. 高级配置​

2.1 多入口配置​

module.exports = {
  entry: {
    app: './src/app.js',
    admin: './src/admin.js'
  },
  
  output: {
    filename: '[name].[contenthash].js',
    path: path.resolve(__dirname, 'dist')
  },
  
  optimization: {
    splitChunks: {
      chunks: 'all',
      cacheGroups: {
        vendors: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendors',
          chunks: 'all'
        }
      }
    }
  }
};

2.2 开发环境配置​

// webpack.dev.js
const { merge } = require('webpack-merge');
const common = require('./webpack.common.js');

module.exports = merge(common, {
  mode: 'development',
  devtool: 'inline-source-map',
  
  devServer: {
    static: './dist',
    hot: true,
    port: 3000,
    proxy: {
      '/api': {
        target: 'http://localhost:8080',
        changeOrigin: true
      }
    }
  }
});

2.3 生产环境配置​

// webpack.prod.js
const { merge } = require('webpack-merge');
const common = require('./webpack.common.js');
const TerserPlugin = require('terser-webpack-plugin');
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');

module.exports = merge(common, {
  mode: 'production',
  devtool: 'source-map',
  
  optimization: {
    minimizer: [
      new TerserPlugin(),
      new CssMinimizerPlugin()
    ],
    splitChunks: {
      chunks: 'all'
    }
  }
});

3. 模块处理​

3.1 Loader 配置​

module.exports = {
  module: {
    rules: [
      // JavaScript/TypeScript
      {
        test: /\.(js|ts)x?$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: [
              '@babel/preset-env',
              '@babel/preset-react',
              '@babel/preset-typescript'
            ]
          }
        }
      },
      
      // CSS/SCSS
      {
        test: /\.(css|scss)$/,
        use: [
          MiniCssExtractPlugin.loader,
          {
            loader: 'css-loader',
            options: {
              modules: true,
              importLoaders: 2
            }
          },
          'postcss-loader',
          'sass-loader'
        ]
      },
      
      // 图片和字体
      {
        test: /\.(png|jpg|gif|svg|eot|ttf|woff|woff2)$/,
        type: 'asset',
        parser: {
          dataUrlCondition: {
            maxSize: 8 * 1024 // 8kb
          }
        }
      }
    ]
  }
};

3.2 Resolve 配置​

module.exports = {
  resolve: {
    // 扩展名
    extensions: ['.js', '.jsx', '.ts', '.tsx'],
    
    // 别名
    alias: {
      '@': path.resolve(__dirname, 'src'),
      'components': path.resolve(__dirname, 'src/components')
    },
    
    // 模块查找目录
    modules: [
      'node_modules',
      path.resolve(__dirname, 'src')
    ]
  }
};

4. 性能优化​

4.1 代码分割​

module.exports = {
  optimization: {
    splitChunks: {
      chunks: 'all',
      minSize: 20000,
      minRemainingSize: 0,
      minChunks: 1,
      maxAsyncRequests: 30,
      maxInitialRequests: 30,
      enforceSizeThreshold: 50000,
      cacheGroups: {
        defaultVendors: {
          test: /[\\/]node_modules[\\/]/,
          priority: -10,
          reuseExistingChunk: true
        },
        default: {
          minChunks: 2,
          priority: -20,
          reuseExistingChunk: true
        }
      }
    }
  }
};

4.2 缓存优化​

module.exports = {
  output: {
    filename: '[name].[contenthash].js',
    path: path.resolve(__dirname, 'dist')
  },
  
  optimization: {
    moduleIds: 'deterministic',
    runtimeChunk: 'single',
    splitChunks: {
      cacheGroups: {
        vendor: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendors',
          chunks: 'all'
        }
      }
    }
  },
  
  // 持久化缓存
  cache: {
    type: 'filesystem',
    buildDependencies: {
      config: [__filename]
    }
  }
};

4.3 Tree Shaking​

// package.json
{
  "sideEffects": [
    "*.css",
    "*.scss"
  ]
}

// webpack.config.js
module.exports = {
  mode: 'production',
  optimization: {
    usedExports: true,
    minimize: true,
    concatenateModules: true
  }
};

5. 插件系统​

5.1 常用插件配置​

const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer');

module.exports = {
  plugins: [
    // HTML 生成
    new HtmlWebpackPlugin({
      template: './src/index.html',
      minify: {
        collapseWhitespace: true,
        removeComments: true
      }
    }),
    
    // CSS 提取
    new MiniCssExtractPlugin({
      filename: '[name].[contenthash].css'
    }),
    
    // 环境变量
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV)
    }),
    
    // 打包分析
    new BundleAnalyzerPlugin({
      analyzerMode: 'static',
      openAnalyzer: false
    })
  ]
};

5.2 自定义插件​

class MyPlugin {
  constructor(options) {
    this.options = options;
  }

  apply(compiler) {
    compiler.hooks.emit.tapAsync(
      'MyPlugin',
      (compilation, callback) => {
        // 在生成文件中，创建一个头部注释
        compilation.assets['main.js'] = {
          source() {
            return `/*! My Plugin */\n${compilation.assets['main.js'].source()}`;
          },
          size() {
            return this.source().length;
          }
        };
        callback();
      }
    );
  }
}

module.exports = MyPlugin;

6. 开发工具​

6.1 Source Map​

module.exports = {
  // 开发环境
  devtool: 'eval-cheap-module-source-map',
  
  // 生产环境
  devtool: 'source-map'
};

6.2 热模块替换​

module.exports = {
  devServer: {
    hot: true,
    liveReload: false
  },
  
  plugins: [
    new webpack.HotModuleReplacementPlugin()
  ]
};

// 在代码中
if (module.hot) {
  module.hot.accept('./print.js', function() {
    console.log('Accepting the updated printMe module!');
    printMe();
  });
}

7. 部署配置​

7.1 多环境配置​

// webpack.config.js
const envConfig = require(`./config/webpack.${process.env.NODE_ENV}.js`);
const commonConfig = require('./config/webpack.common.js');

module.exports = merge(commonConfig, envConfig);

// package.json
{
  "scripts": {
    "dev": "webpack serve --config webpack.dev.js",
    "build:dev": "webpack --config webpack.dev.js",
    "build:prod": "webpack --config webpack.prod.js"
  }
}

7.2 CDN 配置​

module.exports = {
  output: {
    publicPath: 'https://cdn.example.com/assets/',
    filename: '[name].[contenthash].js'
  },
  
  externals: {
    react: 'React',
    'react-dom': 'ReactDOM'
  }
};

参考资源​