Optimizing Tree Shaking in Your Three.js Vite Project

Based on your configuration and dependencies, there are several reasons why tree shaking might not be working effectively in your project. Here are some insights and recommendations to improve your bundle size:

Common Issues with Three.js and Tree Shaking

1. Three.js Import Method: The way you import Three.js can significantly impact tree shaking.

2. Dependencies with Side Effects: Some of your dependencies (like GSAP, Matter.js) might not be fully tree-shakable.

3. Missing Configuration: Your current Rollup/Vite config might need additional optimization settings.

Recommended Adjustments

1. Use Proper Three.js Imports

Instead of importing the entire Three.js library, use specific imports:

JAVASCRIPTCopied
// Bad (imports everything)
import * as THREE from 'three';

// Good (only imports what you need)
import { Scene, PerspectiveCamera, WebGLRenderer } from 'three';
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js';

2. Add Tree Shaking Configuration

Enhance your Vite config with these optimizations:

JAVASCRIPTCopied
// vite.config.js
import { defineConfig } from 'vite';
import { resolve } from 'path';

export default defineConfig({
  base: './',
  build: {
    outDir: 'dist',
    rollupOptions: {
      input: resolve(__dirname, 'index.html'),
      output: {
        entryFileNames: 'js/[name]-[hash].js',
        chunkFileNames: 'js/[name]-[hash].js',
        assetFileNames: assetInfo => {
          if (assetInfo.name && assetInfo.name.endsWith('.css')) {
            return 'css/[name]-[hash][extname]';
          }
          if (assetInfo.name && /\.(png|jpe?g|gif|svg)$/.test(assetInfo.name)) {
            return 'img/[name]-[hash][extname]';
          }
          return '[name]-[hash][extname]';
        },
        manualChunks: {
          three: ['three'],
          gsap: ['gsap'],
          vendor: ['matter-js', 'lil-gui', 'stats.js']
        }
      }
    },
    minify: 'terser',
    terserOptions: {
      compress: {
        drop_console: true,
        pure_funcs: ['console.log']
      }
    }
  },
  optimizeDeps: {
    include: ['three']
  }
});

3. Analyze Your Bundle

Add a bundle analyzer to identify large dependencies:

BASHCopied
npm install rollup-plugin-visualizer --save-dev

Then update your Vite config:

JAVASCRIPTCopied
import { visualizer } from 'rollup-plugin-visualizer';

// Add to your config
plugins: [
  visualizer({
    open: true,
    gzipSize: true,
    brotliSize: true,
  })
]

4. Remove Unused Dependencies

Your package.json includes dependencies that might not be needed:

• ssh2-sftp-client - Only needed for deployment, move to devDependencies
• If you're not using all of matter-js, lil-gui, or stats.js, consider removing them

5. Use Dynamic Imports for Three.js Loaders

For loaders that are only used once during initialization:

JAVASCRIPTCopied
async function loadModel() {
  const { GLTFLoader } = await import('three/examples/jsm/loaders/GLTFLoader.js');
  const loader = new GLTFLoader();
  // Load your model
}

6. Check for Side Effects

Add "sideEffects": false to your package.json to help tree shaking, but be careful if your code relies on side effects.

These adjustments should significantly improve tree shaking and reduce your bundle size. The most important change is to use specific imports from Three.js rather than importing the entire library.