The "Dual-Package" Hazard
With the advent of React 18, Server Components, and the aggressive push for ESM (ECMAScript Modules), the library authoring landscape became a minefield. The "Dual-Package Hazard"—ensuring a library works seamlessly in both CommonJS (Node) and ESM (Bundlers) while maintaining sideEffects purity for tree-shaking—became a critical architectural challenge.
I established the React 18 Tools organization to solve these infrastructure problems, providing a standardized "Build OS" for modern library authors.
Architectural Components
1. The Build Engine (react18-tools CLI)
Most build tools are designed for applications. Library builds require different constraints: creating discrete outputs for main, module, and exports fields without bundling dependencies.
- Architecture: Built on top of Esbuild for speed, but wrapped with a custom AST analysis layer.
- Innovation: implemented "Smart Entry Point Detection." Instead of manually configuring inputs, the tool walks the directory tree, analyzes
package.jsonexports, and constructs the dependency graph automatically.
2. Solving React 18 Concurrency & Storage
React 18's concurrent rendering features broke many traditional state management patterns (tearing issues).
react18-global-store: I architected a state management solution specifically for the concurrent era.- Mechanism: Utilizes
useSyncExternalStore(the shim and native implementation) to ensure atomic updates across the component tree, preventing visual tearing during high-priority interruptible renders. - DX: Zero-boilerplate setup with automatic type inference.
- Mechanism: Utilizes
3. The "Tree-Shaking" Guardian
Many UI libraries accidentally ship dead code because of improper sideEffects flagging in package.json or top-level function calls.
- Validation Pipeline: Created a CI/CD step that effectively "audits" the final bundle. It imports specific named exports and measures the bundle impact, failing the build if the "Hello World" import pulls in the entire library.
Deep Dive: The CJS/ESM Interop Bridge
One of the hardest problems in Node.js tooling is supporting import { named } from 'pkg' in ESM while supporting const { named } = require('pkg') in CJS, specifically when using default exports.
- The Hack: I implemented a "Proxy Export" pattern during the build phase.
- Implementation: The build tool generates a thin CJS wrapper that mimics the ESM namespace object. This allows consumers to use modern syntax without breaking legacy Node.js environments.
Impact & Metrics
- Adoption: The tools and libraries under this umbrella (only counting my own packages) have seen over 5989834 combined downloads.
- Performance: Reduced build times for monitored monorepos by ~60% by switching from Rollup-based pipelines to this custom Esbuild implementation.
- Standardization: This infrastructure now serves as the backbone for my entire open-source portfolio, allowing me to ship features rather than fighting configuration files.