Bundlers combine dozens or hundreds of JavaScript modules into optimized files a browser can load efficiently — Webpack dominated for years, and Vite has become the modern default for new projects.
Why Bundling Is Necessary at All
Loading hundreds of individual <script> tags (one per module) is slow due to request overhead, and older browsers didn’t support ES modules natively at all — bundlers solve both by combining, minifying, and tree-shaking (removing unused code) before shipping to production.
# Vite: near-instant dev server startup via native ES modules + esbuild npm create vite@latest my-app npm run dev # starts almost instantly, even on large projects # Webpack: more configuration, but extremely mature plugin ecosystem npx webpack serve --mode development
Why Vite Feels Faster
Webpack bundles your entire application before the dev server can even start. Vite serves your source files as native ES modules directly to the browser during development, bundling only for the final production build — this is the core architectural difference behind Vite’s near-instant startup times on large projects.