TypeScript Library Development
Patterns for authoring high-quality TypeScript libraries, extracted from studying unocss, shiki, unplugin, vite, vitest, vueuse, zod, trpc, drizzle-orm, and more.
When to Use Starting a new TypeScript library (single or monorepo) Setting up package.json exports for dual CJS/ESM Configuring tsconfig for library development Choosing build tools (tsdown, unbuild) Designing type-safe APIs (builder, factory, plugin patterns) Writing advanced TypeScript types Setting up vitest for library testing Configuring release workflow and CI
For Nuxt module development: use nuxt-modules skill
Quick Reference Working on... Load file New project setup references/project-setup.md Package exports references/package-exports.md tsconfig options references/typescript-config.md Build configuration references/build-tooling.md API design patterns references/api-design.md Type inference tricks references/type-patterns.md Testing setup references/testing.md Release workflow references/release.md CI/CD setup references/ci-workflows.md Key Principles ESM-first: "type": "module" with .mjs outputs Dual format: always support both CJS and ESM consumers moduleResolution: "Bundler" for modern TypeScript tsdown for most builds, unbuild for complex cases Smart defaults: detect environment, don't force config Tree-shakeable: lazy getters, proper sideEffects: false
Token efficiency: Main skill ~300 tokens, each reference ~800-1200 tokens