tooling

A monorepo contains multiple packages/projects in one repository. Use tools like Turborepo, Nx, or pnpm workspaces for dependency management, shared configs, and efficient builds. Benefits include code sharing, atomic changes, and unified tooling.

Create custom ESLint rules by writing AST visitors that detect patterns and report errors. Rules receive context with report() for violations. Package multiple rules as a plugin with rules and recommended configs. Use AST Explorer to understand code structure.

Babel transforms modern JavaScript to compatible versions using plugins (individual transforms) and presets (plugin collections). Configure via babel.config.js with presets like @babel/preset-env for automatic browser targeting and plugins for specific features.

Create a Dockerfile with multi-stage builds: first stage installs dependencies and builds, second stage copies only production files for smaller images. Use .dockerignore, optimize layer caching, and consider Node.js-specific best practices like running as non-root.

Optimize builds with: incremental/cached builds (Turborepo, Nx), parallel processing, using faster tools (esbuild, SWC), persistent caching, avoiding unnecessary work (affected only), and proper CI caching. Profile builds to find bottlenecks.