Discuss build options in Vite

Vite's build system is designed to produce highly optimized static assets for production deployment. When you run vite build, Vite leverages Rollup under the hood (with Oxc in newer versions) to bundle your application, applying sophisticated optimizations like code splitting, tree-shaking, and asset minification. The build process is highly configurable through both command-line flags and the build section of your Vite configuration file, giving you fine-grained control over every aspect of the production output.

The vite build command accepts numerous flags that directly influence the build output. These options can be specified on the command line or through the configuration file, with CLI flags taking precedence.

Vite's build.target option controls the browser compatibility level for the final bundle. Starting with Vite 6+, the default target is 'baseline-widely-available', which targets browsers in the Baseline Widely Available set as of 2026-01-01: Chrome 111+, Edge 111+, Firefox 114+, and Safari 16.4+. For legacy browser support, you can specify lower targets like 'es2015' or use the @vitejs/plugin-legacy to generate fallback chunks.

Beyond basic options, Vite provides sophisticated controls for optimizing your production build. These settings allow you to fine-tune how assets are processed, how code is split, and how dependencies are handled.

For library authors, Vite offers a dedicated library mode through the build.lib option. This mode configures Rollup specifically for library distribution, producing optimized bundles in multiple formats (ES, UMD, CJS) with proper externalization of dependencies. The library mode automatically handles CSS extraction, file naming, and global variable exposure for UMD builds.

Vite natively supports multi-page applications (MPAs) through configuration of multiple HTML entry points. Instead of a single index.html, you can specify multiple HTML files in build.rollupOptions.input. During development, you can navigate directly to these pages, and during build, Vite generates separate HTML files for each entry point with optimized assets.

Vite provides sophisticated code splitting capabilities through build.rollupOptions.output.manualChunks. This allows you to control how dependencies are grouped into separate chunks, optimizing caching and load performance. You can create custom chunking strategies based on module patterns, dependencies, or custom logic.

When building for integration with backend frameworks, Vite can generate manifest files (build.manifest and build.ssrManifest). These JSON files map original source filenames to their hashed production versions, enabling server frameworks to render correct asset links. The SSR manifest specifically helps determine style links and asset preload directives for server-side rendering.

The --watch flag enables Rollup's watcher, rebuilding whenever source files change. This is particularly useful during development of libraries or when integrating with other build systems. You can customize watch behavior through build.watch options, including settings for file system polling, ignore patterns, and build delay.

Vite includes a preview server command (vite preview) that serves the production build locally. This allows you to verify the built output before deployment, ensuring that all assets load correctly and the application behaves as expected in a production-like environment. The preview server respects the same base path and configuration as the production build.