Webpack Cheat Sheet¶

Webpack - Static Module Bundler

Webpack è un module bundler statico per applicazioni JavaScript moderne. Quando webpack elabora la tua applicazione, internamente costruisce un grafo delle dipendenze da uno o più punti di ingresso e poi combina tutti i moduli di cui il tuo progetto necessita in uno o più bundle.

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Sommario¶

Installazione
Configurazione Base
Punti di Ingresso
Output
Loader
Plugin
Modalità
Server di Sviluppo
Code Splitting
Ottimizzazione
Risoluzione Moduli
Sostituzione Moduli a Caldo
Variabili di Ambiente
Build di Produzione
Configurazione Avanzata
Prestazioni
Risoluzione dei Problemi
Migliori Pratiche

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Install webpack globally¶

npm install -g webpack webpack-cli

Check version¶

webpack --version

### Local Installation (Recommended)
```bash
# Initialize npm project
npm init -y

# Install webpack locally
npm install --save-dev webpack webpack-cli

# Install webpack dev server
npm install --save-dev webpack-dev-server

# Install common loaders and plugins
npm install --save-dev html-webpack-plugin css-loader style-loader file-loader url-loader

Package.json Scripts¶

{
  "scripts": {
    "build": "webpack --mode production",
    "dev": "webpack --mode development",
    "start": "webpack serve --mode development",
    "watch": "webpack --mode development --watch"
  }
}

Basic Configuration¶

Minimal webpack.config.js¶

const path = require('path');

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

Complete Basic Configuration¶

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.[contenthash].js',
    path: path.resolve(__dirname, 'dist'),
    clean: true
  },
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: ['style-loader', 'css-loader']
      },
      {
        test: /\.(png|svg|jpg|jpeg|gif)$/i,
        type: 'asset/resource'
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/index.html'
    })
  ]
};

TypeScript Configuration¶

const path = require('path');

module.exports = {
  entry: './src/index.ts',
  module: {
    rules: [
      {
        test: /\.tsx?$/,
        use: 'ts-loader',
        exclude: /node_modules/
      }
    ]
  },
  resolve: {
    extensions: ['.tsx', '.ts', '.js']
  },
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

Entry Points¶

Single Entry Point¶

module.exports = {
  entry: './src/index.js'
};

Multiple Entry Points¶

module.exports = {
  entry: {
    main: './src/index.js',
    vendor: './src/vendor.js'
  }
};

Dynamic Entry Points¶

module.exports = {
  entry: () => {
    return {
      main: './src/index.js',
      admin: './src/admin.js'
    };
  }
};

Entry with Dependencies¶

module.exports = {
  entry: {
    main: {
      import: './src/index.js',
      dependOn: 'shared'
    },
    admin: {
      import: './src/admin.js',
      dependOn: 'shared'
    },
    shared: 'lodash'
  }
};

Output¶

Basic Output Configuration¶

const path = require('path');

module.exports = {
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

Multiple Entry Output¶

module.exports = {
  entry: {
    main: './src/index.js',
    admin: './src/admin.js'
  },
  output: {
    filename: '[name].bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

Output with Hashing¶

module.exports = {
  output: {
    filename: '[name].[contenthash].js',
    path: path.resolve(__dirname, 'dist'),
    clean: true
  }
};

Public Path Configuration¶

module.exports = {
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist'),
    publicPath: '/assets/'
  }
};

Library Output¶

module.exports = {
  output: {
    filename: 'my-library.js',
    path: path.resolve(__dirname, 'dist'),
    library: {
      name: 'MyLibrary',
      type: 'umd'
    }
  }
};

Loaders¶

CSS Loaders¶

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: ['style-loader', 'css-loader']
      },
      {
        test: /\.s[ac]ss$/i,
        use: ['style-loader', 'css-loader', 'sass-loader']
      },
      {
        test: /\.less$/i,
        use: ['style-loader', 'css-loader', 'less-loader']
      }
    ]
  }
};

JavaScript Loaders¶

module.exports = {
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      },
      {
        test: /\.tsx?$/,
        use: 'ts-loader',
        exclude: /node_modules/
      }
    ]
  }
};

File Loaders¶

module.exports = {
  module: {
    rules: [
      {
        test: /\.(png|svg|jpg|jpeg|gif)$/i,
        type: 'asset/resource'
      },
      {
        test: /\.(woff|woff2|eot|ttf|otf)$/i,
        type: 'asset/resource'
      },
      {
        test: /\.(csv|tsv)$/i,
        use: ['csv-loader']
      },
      {
        test: /\.xml$/i,
        use: ['xml-loader']
      }
    ]
  }
};

Asset Modules¶

module.exports = {
  module: {
    rules: [
      {
        test: /\.png/,
        type: 'asset/resource'
      },
      {
        test: /\.html/,
        type: 'asset/resource'
      },
      {
        test: /\.txt/,
        type: 'asset/source'
      },
      {
        test: /\.jpg/,
        type: 'asset',
        parser: {
          dataUrlCondition: {
            maxSize: 4 * 1024 // 4kb
          }
        }
      }
    ]
  }
};

Loader Options¶

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          'style-loader',
          {
            loader: 'css-loader',
            options: {
              modules: true,
              sourceMap: true
            }
          }
        ]
      }
    ]
  }
};

Plugins¶

HTML Webpack Plugin¶

const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlWebpackPlugin({
      template: './src/index.html',
      filename: 'index.html',
      inject: 'body'
    })
  ]
};

Extract CSS Plugin¶

const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [MiniCssExtractPlugin.loader, 'css-loader']
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: '[name].[contenthash].css'
    })
  ]
};

Define Plugin¶

const webpack = require('webpack');

module.exports = {
  plugins: [
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify('production'),
      'process.env.API_URL': JSON.stringify('https://api.example.com')
    })
  ]
};

Copy Webpack Plugin¶

const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = {
  plugins: [
    new CopyWebpackPlugin({
      patterns: [
        { from: 'public', to: 'public' },
        { from: 'assets/images', to: 'images' }
      ]
    })
  ]
};

Bundle Analyzer Plugin¶

const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;

module.exports = {
  plugins: [
    new BundleAnalyzerPlugin({
      analyzerMode: 'static',
      openAnalyzer: false
    })
  ]
};

Clean Webpack Plugin¶

const { CleanWebpackPlugin } = require('clean-webpack-plugin');

module.exports = {
  plugins: [
    new CleanWebpackPlugin()
  ]
};

Mode¶

Development Mode¶

module.exports = {
  mode: 'development',
  devtool: 'eval-source-map'
};

Production Mode¶

module.exports = {
  mode: 'production',
  devtool: 'source-map'
};

Mode-specific Configuration¶

module.exports = (env, argv) => {
  const isProduction = argv.mode === 'production';

  return {
    mode: argv.mode,
    devtool: isProduction ? 'source-map' : 'eval-source-map',
    optimization: {
      minimize: isProduction
    }
  };
};

Development Server¶

Basic Dev Server¶

module.exports = {
  devServer: {
    static: './dist',
    port: 3000,
    open: true
  }
};

Advanced Dev Server Configuration¶

module.exports = {
  devServer: {
    static: {
      directory: path.join(__dirname, 'dist')
    },
    compress: true,
    port: 3000,
    hot: true,
    open: true,
    historyApiFallback: true,
    proxy: {
      '/api': {
        target: 'http://localhost:8080',
        changeOrigin: true,
        pathRewrite: {
          '^/api': ''
        }
      }
    }
  }
};

HTTPS Dev Server¶

module.exports = {
  devServer: {
    https: true,
    // or with custom certificates
    https: {
      key: fs.readFileSync('/path/to/server.key'),
      cert: fs.readFileSync('/path/to/server.crt'),
      ca: fs.readFileSync('/path/to/ca.pem')
    }
  }
};

Code Splitting¶

Entry Point Splitting¶

module.exports = {
  entry: {
    main: './src/index.js',
    vendor: './src/vendor.js'
  }
};

Dynamic Imports¶

// In your JavaScript code
import('./math.js').then(math => {
  console.log(math.add(16, 26));
});

// Or with async/await
async function loadMath() {
  const math = await import('./math.js');
  return math.add(16, 26);
}

SplitChunks Plugin¶

module.exports = {
  optimization: {
    splitChunks: {
      chunks: 'all',
      cacheGroups: {
        vendor: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendors',
          chunks: 'all'
        },
        common: {
          name: 'common',
          minChunks: 2,
          chunks: 'all',
          enforce: true
        }
      }
    }
  }
};

Advanced Code Splitting¶

module.exports = {
  optimization: {
    splitChunks: {
      chunks: 'all',
      minSize: 20000,
      maxSize: 244000,
      cacheGroups: {
        default: {
          minChunks: 2,
          priority: -20,
          reuseExistingChunk: true
        },
        vendor: {
          test: /[\\/]node_modules[\\/]/,
          priority: -10,
          reuseExistingChunk: true
        },
        react: {
          test: /[\\/]node_modules[\\/](react|react-dom)[\\/]/,
          name: 'react',
          chunks: 'all'
        }
      }
    }
  }
};

Optimization¶

Minification¶

const TerserPlugin = require('terser-webpack-plugin');

module.exports = {
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          compress: {
            drop_console: true
          }
        }
      })
    ]
  }
};

CSS Optimization¶

```javascript const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');

module.exports = { optimization: { minimizer: [ new CssMinimizerPlugin() ] } }; ### Tree Shaking ### Eliminazione del codice mortojavascript module.exports = { mode: 'production', optimization: { usedExports: true, sideEffects: false } }; ### Runtime Chunk ### Chunk di Runtimejavascript module.exports = { optimization: { runtimeChunk: 'single' } }; ### Module Concatenation ### Concatenazione dei Modulijavascript module.exports = { optimization: { concatenateModules: true } }; ## Module Resolution ## Risoluzione dei Modulijavascript const path = require('path');

module.exports = { resolve: { extensions: ['.js', '.jsx', '.ts', '.tsx', '.json'], alias: { '@': path.resolve(__dirname, 'src'), 'components': path.resolve(__dirname, 'src/components'), 'utils': path.resolve(__dirname, 'src/utils') }, modules: [ 'node_modules', path.resolve(__dirname, 'src') ] } }; ### Resolve Configuration ### Configurazione di Risoluzionejavascript module.exports = { resolve: { fallback: { "fs": false, "path": require.resolve("path-browserify"), "crypto": require.resolve("crypto-browserify") } } }; ### Resolve Fallback ### Fallback di Risoluzionejavascript const webpack = require('webpack');

module.exports = { devServer: { hot: true }, plugins: [ new webpack.HotModuleReplacementPlugin() ] }; ## Hot Module Replacement ## Sostituzione a Caldo dei Modulijavascript // In your JavaScript modules if (module.hot) { module.hot.accept('./library.js', function() { console.log('Accepting the updated library module!'); // Re-render or update your app }); } ### Enable HMR ### Abilitare HMRjavascript const ReactRefreshWebpackPlugin = require('@pmmmwh/react-refresh-webpack-plugin');

module.exports = { module: { rules: [ { test: /.[jt]sx?$/, exclude: /node_modules/, use: [ { loader: 'babel-loader', options: { plugins: ['react-refresh/babel'] } } ] } ] }, plugins: [ new ReactRefreshWebpackPlugin() ] }; ### HMR in Code ### HMR nel Codicejavascript const webpack = require('webpack');

module.exports = { plugins: [ new webpack.DefinePlugin({ 'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV), 'process.env.API_URL': JSON.stringify(process.env.API_URL || 'http://localhost:3000') }) ] }; ### React Hot Reload ### React Hot Reloadjavascript module.exports = (env, argv) => { const isProduction = argv.mode === 'production';

return { mode: argv.mode, plugins: [ new webpack.DefinePlugin({ 'process.env.NODE_ENV': JSON.stringify(argv.mode), 'process.env.API_URL': JSON.stringify( isProduction ? 'https://api.production.com' : 'http://localhost:3000' ) }) ] }; }; ## Environment Variables ## Variabili d'Ambientejavascript const Dotenv = require('dotenv-webpack');

module.exports = { plugins: [ new Dotenv({ path: './.env', safe: true, systemvars: true }) ] }; ### DefinePlugin for Environment Variables ### DefinePlugin per Variabili d'Ambientejavascript const path = require('path'); const HtmlWebpackPlugin = require('html-webpack-plugin'); const MiniCssExtractPlugin = require('mini-css-extract-plugin'); const CssMinimizerPlugin = require('css-minimizer-webpack-plugin'); const TerserPlugin = require('terser-webpack-plugin');

module.exports = { mode: 'production', entry: './src/index.js', output: { filename: '[name].[contenthash].js', path: path.resolve(__dirname, 'dist'), clean: true }, module: { rules: [ { test: /.js$/, exclude: /node_modules/, use: { loader: 'babel-loader', options: { presets: ['@babel/preset-env'] } } }, { test: /\.css$/, use: [MiniCssExtractPlugin.loader, 'css-loader'] } ] }, plugins: [ new HtmlWebpackPlugin({ template: './src/index.html', minify: { removeComments: true, collapseWhitespace: true, removeRedundantAttributes: true, useShortDoctype: true, removeEmptyAttributes: true, removeStyleLinkTypeAttributes: true, keepClosingSlash: true, minifyJS: true, minifyCSS: true, minifyURLs: true } }), new MiniCssExtractPlugin({ filename: '[name].[contenthash].css' }) ], optimization: { minimize: true, minimizer: [ new TerserPlugin({ terserOptions: { compress: { drop_console: true } } }), new CssMinimizerPlugin() ], splitChunks: { chunks: 'all', cacheGroups: { vendor: { test: /[\/]node_modules[\/]/, name: 'vendors', chunks: 'all' } } }, runtimeChunk: 'single' } }; ### Environment-specific Configuration ### Configurazione Specifica dell'Ambientejson { "scripts": { "build": "webpack --mode production", "build:analyze": "webpack --mode production --env analyze", "build:stats": "webpack --mode production --json > stats.json" } } ### DotEnv Plugin ### Plugin DotEnvjavascript const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = { entry: { home: './src/home.js', about: './src/about.js', contact: './src/contact.js' }, plugins: [ new HtmlWebpackPlugin({ filename: 'home.html', template: './src/home.html', chunks: ['home'] }), new HtmlWebpackPlugin({ filename: 'about.html', template: './src/about.html', chunks: ['about'] }), new HtmlWebpackPlugin({ filename: 'contact.html', template: './src/contact.html', chunks: ['contact'] }) ] }; ## Production Build ## Build di Produzionejavascript const ModuleFederationPlugin = require('@module-federation/webpack');

module.exports = { plugins: [ new ModuleFederationPlugin({ name: 'shell', remotes: { mfe1: 'mfe1@http://localhost:3001/remoteEntry.js', mfe2: 'mfe2@http://localhost:3002/remoteEntry.js' } }) ] }; ### Production Configuration ### Configurazione di Produzionejavascript const WorkboxPlugin = require('workbox-webpack-plugin');

module.exports = { plugins: [ new WorkboxPlugin.GenerateSW({ clientsClaim: true, skipWaiting: true }) ] }; ### Build Scripts ### Script di Buildjavascript // custom-loader.js module.exports = function(source) { // Transform the source return export default ${JSON.stringify(source)}; };

// webpack.config.js module.exports = { module: { rules: [ { test: /.custom$/, use: path.resolve(__dirname, 'custom-loader.js') } ] } }; ## Advanced Configuration ## Configurazione Avanzatajavascript class MyCustomPlugin { apply(compiler) { compiler.hooks.emit.tapAsync('MyCustomPlugin', (compilation, callback) => { console.log('This is an example plugin!'); callback(); }); } }

module.exports = { plugins: [ new MyCustomPlugin() ] }; ### Multi-page Application ### Applicazione Multi-paginajavascript module.exports = { performance: { maxAssetSize: 250000, maxEntrypointSize: 250000, hints: 'warning' } }; ### Micro-frontends Configuration ### Configurazione Micro-frontendjavascript // Dynamic imports for lazy loading const LazyComponent = React.lazy(() => import('./LazyComponent'));

// Webpack magic comments import( /* webpackChunkName: "my-chunk-name" / / webpackMode: "lazy" / './modules/my-module.js' ); ### Prefetching and Preloadingjavascript // Prefetch import( / webpackPrefetch: true */ './modules/LoginModal.js' );

// Preload import( /* webpackPreload: true */ './modules/ChartingLibrary.js' ); ### Analisi del Bundlebash

Generate stats file¶

webpack --profile --json > stats.json

Analyze with webpack-bundle-analyzer¶

npx webpack-bundle-analyzer stats.json

Use webpack-bundle-analyzer plugin¶

npm install --save-dev webpack-bundle-analyzer ## Risoluzione dei Problemijavascript // Check resolve configuration module.exports = { resolve: { extensions: ['.js', '.jsx', '.ts', '.tsx'], alias: { '@': path.resolve(__dirname, 'src') } } }; #### Modulo Non Trovatobash

Increase Node.js memory limit¶

node --max-old-space-size=4096 node_modules/.bin/webpack

Or in package.json¶

{ "scripts": { "build": "node --max-old-space-size=4096 node_modules/.bin/webpack" } } #### Problemi di Memoriajavascript module.exports = { // Use cache cache: { type: 'filesystem' },

// Exclude node_modules from babel-loader module: { rules: [ { test: /.js$/, exclude: /node_modules/, use: 'babel-loader' } ] },

// Use thread-loader for expensive loaders module: { rules: [ { test: /.js$/, use: [ 'thread-loader', 'babel-loader' ] } ] } }; #### Tempi di Build Lentijavascript module.exports = { // Different source map options devtool: 'eval-source-map', // Development devtool: 'source-map', // Production devtool: 'cheap-module-source-map', // Faster builds devtool: false // No source maps }; #### Problemi con Source Mapjavascript module.exports = { stats: { colors: true, modules: false, children: false, chunks: false, chunkModules: false } }; ### Configurazione di Debugjavascript // webpack.common.js const path = require('path'); const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = { entry: './src/index.js', plugins: [ new HtmlWebpackPlugin({ template: './src/index.html' }) ] };

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

module.exports = merge(common, { mode: 'development', devtool: 'eval-source-map', devServer: { static: './dist' } });

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

module.exports = merge(common, { mode: 'production', devtool: 'source-map' }); ```## Migliori Pratiche

Organizzazione della Configurazione¶

Ottimizzazione delle Prestazioni¶

Usa la modalità di produzione per le ottimizzazioni
Abilita tree shaking per rimuovere codice morto
Dividi i chunk per migliorare la cache
Usa content hashing per la cache a lungo termine
Minimizza la dimensione del bundle con loader e plugin appropriati

Esperienza di Sviluppo¶

Usa HMR per uno sviluppo più veloce
Configura source map per il debug
Imposta un server di sviluppo con proxy per chiamate API
Usa webpack-bundle-analyzer per capire la composizione del bundle

Organizzazione del Codice¶

Separa la configurazione per ambienti diversi
Usa alias per import più puliti
Organizza i loader per tipo di file
Raggruppa plugin correlati

Riepilogo¶

Webpack è un potente e flessibile module bundler che può gestire requisiti di build complessi per applicazioni web moderne. Caratteristiche principali includono:

Bundling dei Moduli: Combina moduli in bundle ottimizzati
Loader: Trasformano file durante il processo di build
Plugin: Estendono la funzionalità di webpack
Code Splitting: Divide il codice in chunk più piccoli per migliori prestazioni
Hot Module Replacement: Aggiorna moduli senza ricaricare la pagina
Tree Shaking: Rimuove codice inutilizzato dai bundle
Gestione Asset: Gestisce vari tipi di file e asset

Padroneggiando la configurazione di webpack e seguendo le migliori pratiche, puoi creare processi di build efficienti che migliorano sia l'esperienza di sviluppo che le prestazioni dell'applicazione.