father-build (UmiJS Father)

Father-build is the primary library build tool within the UmiJS ecosystem, often referred to simply as 'Father'. Currently stable at version 4.6.17, it's a powerful and highly configurable solution for packaging JavaScript and TypeScript libraries. It leverages Rollup for robust bundling and integrates esbuild for performance optimizations across various output formats, including ESM, CJS, UMD, and a 'bundless' mode for individual file compilation. The project maintains a very active development pace, frequently issuing multiple minor and patch updates each month, incorporating new features like CSS extraction, enhanced JSX runtime support, and parallel bundless compilation. Key differentiators include comprehensive TypeScript support (shipping its own types and regularly upgrading internal TS versions), flexible configuration via `father.config.ts` using `defineConfig`, and a strong focus on delivering optimized output for diverse JavaScript environments. It aims to streamline library development by abstracting complex build configurations and providing a consistent developer experience.