Code Splitting

Code splitting divides application code into smaller chunks that load on demand, reducing initial payload size. Modern bundlers like Webpack support dynamic imports for this purpose.

// Dynamically import a heavy module when needed
const loadHeavyModule = async () => {
  try {
    const heavyModule = await import(/* webpackChunkName: 'heavy-module' */ './heavyModule');
    heavyModule.initialize();
  } catch (error) {
    console.error('Module loading failed:', error);
  }
};

Dead Code Elimination

Remove unused code during build process to reduce bundle size and prevent potential bugs.

// Webpack configuration for dead code elimination
const TerserPlugin = require('terser-webpack-plugin');

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

Resource Compression

Minify JavaScript, CSS, and HTML files using appropriate tools:

• JavaScript: Terser, UglifyJS
• CSS: CSSNano, csso
• HTML: HTMLMinifier
• Images: Squoosh, Sharp

Tree Shaking

Eliminate unused code from ES6 modules through static analysis during bundling.

// Webpack production mode enables tree shaking automatically
module.exports = {
  mode: 'production',
  optimization: {
    usedExports: true
  }
};

Dependency Optimization

Optimize third-party dependencies by:

• Choosing lightweight alternatives
• Importing only necessary modules
• Using CDN-hosted libraries

External Dependencies

Configure external dependencies to exclude them from the bundle.

// Webpack externals configuration
module.exports = {
  externals: {
    lodash: '_',
    moment: 'moment'
  }
};

Persistent Caching

Separate vendor code from appplication code and implement long-term caching strategies.

Bundle Analysis

Use analysis tools to identify optimization opportunities.

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

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

Lazy Loading

Defer loading of non-critical resources until needed.

// React lazy loading example
import React, { Suspense, lazy } from 'react';

const AsyncComponent = lazy(() => import('./AsyncComponent'));

const App = () => (
  <Suspense fallback={<div>Loading component...</div>}>
    <AsyncComponent />
  </Suspense>
);

Resource Hints

Use preload and prefetch to optimize resource loading.

<!-- Preload critical resources -->
<link rel="preload" href="critical.css" as="style">

<!-- Prefetch likely future resources -->
<link rel="prefetch" href="next-page.js" as="script">

Image Optimization

Implement modern image formats and optimization techniques:

• Use WebP format with fallbacks
• Implement responsive images with srcset
• Compress images without quality loss
• Use lazy loading for below-fold images

Compression Techniques

Enable GZip compression on the server and consider Brotli for better compression ratios.

Server Optimization

Improve server resposne time through:

• Adequate hardware resources
• Efficient database queries
• Proper caching strategies
• Load balancing

Browser Caching

Leverage browser caching with appropriate cache headers and service workers.

CDN Implementation

Use Content Delivery Networks to serve assets from geographically distributed servers.

CSS Optimization

Optimize CSS delivery through:

• Critical CSS inlining
• Unused CSS removal
• CSS minification

// PurgeCSS configuration for Webpack
const PurgeCSSPlugin = require('purgecss-webpack-plugin');
const glob = require('glob');

module.exports = {
  plugins: [
    new PurgeCSSPlugin({
      paths: glob.sync(`${path.join(__dirname, 'src')}/**/*`, { nodir: true })
    })
  ]
};

HTTP Request Reduction

Minimize HTTP requests by:

• Combining files
• Using CSS sprites
• Implementing asset concatenation
• Reducing external resources

Script Optimization

Optimize JavaScript execution through:

• Async and defer attributes
• Code splitting
• Minimizing main thread work

Build Optimization

Configure environment-specific builds for development and production.

// Environment-specific Webpack configuration
module.exports = (env) => ({
  devtool: env.production ? false : 'source-map',
  mode: env.production ? 'production' : 'development'
});