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Rspack Production Configuration

The rspack.production.config.ts specializes the build for deployment, focusing on three core goals: Performance, Size, and Security.

1. Advanced Minification​

In production mode, the framework applies a multi-layered minification strategy:

  • JavaScript: Utilizes SwcJsMinimizerRspackPlugin (or TerserPlugin as a fallback). It performs dead-code elimination, scope hoisting, and variable mangling.
  • CSS: Utilizes LightningCssMinimizerRspackPlugin. This is significantly more efficient than standard CSS minifiers as it understands CSS syntax deeply, allowing for advanced tree-shaking of unused styles.

2. Payload Optimization​

To minimize the Time to Interactive (TTI), several asset optimizations are applied:

  • Brotli & Gzip Compression: The CompressionPlugin generates pre-compressed versions of all static files. This allows the web server (Nginx/Vercel) to serve these files instantly without on-the-fly compression overhead.
  • Tree Shaking: Enabled globally for all packages, ensuring that only the used parts of libraries (like lodash-es) are included in the final bundles.

3. Plugins Active in Production​

Note that several plugins commonly associated with production output are actually configured in the base config (they are not production-only):

  • CssExtractRspackPlugin: Extracts CSS into separate files rather than inlining them into JavaScript. This is essential for cache-friendly delivery and FCP optimization. (Configured in the base config.)
  • Workbox InjectManifest: Generates a Service Worker that handles offline capabilities, caching strategies (Stale-While-Revalidate), and faster repeat visits. (Configured in the base config.)
  • Analyze Mode: If triggered via --analyze, an Rsdoctor bundle analysis is generated, allowing developers to identify and eliminate "fat" dependencies.

4. Source Map Strategy​

The framework uses SourceMapDevToolPlugin (configured in the base config, not production-only) to generate external source maps (.map files). These are not served to the end user by default but are preserved for debugging production errors in tools like Sentry or Instana.