Vite Patterns

Environment Variables

• Only VITE_ prefixed vars are exposed to client code — DB_PASSWORD stays server-side, VITE_API_URL is bundled
• Access via import.meta.env.VITE_* not process.env — process.env is Node-only and undefined in browser
• .env.local overrides .env and is gitignored by default — use for local secrets
• import.meta.env.MODE is development or production — use for conditional logic, not NODE_ENV

CommonJS Compatibility

• Pure ESM by default — CommonJS packages need optimizeDeps.include for pre-bundling
• require() doesn't work in Vite — use import or createRequire from module for dynamic requires
• Some packages ship broken ESM — add to ssr.noExternal or optimizeDeps.exclude and let Vite transform them
• Named exports from CommonJS may fail — use default import and destructure: import pkg from 'pkg'; const { method } = pkg

Dependency Pre-bundling

• Vite pre-bundles dependencies on first run — delete node_modules/.vite to force rebuild after package changes
• Large dependencies slow down dev server start — add rarely-changing ones to optimizeDeps.include for persistent cache
• Linked local packages (npm link) aren't pre-bundled — add to optimizeDeps.include explicitly
• optimizeDeps.force: true rebuilds every time — only for debugging, kills dev performance