ts-library

name ts-library description Use when authoring TypeScript libraries or npm packages - covers project setup, package.json exports, build tooling (tsdown/unbuild), API design patterns, type inference tricks, testing, and publishing to npm. Use when bundling, configuring dual CJS/ESM output, or setting up release workflows. license MIT 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 ESLint config references/eslint-config.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 Loading Files Consider loading these reference files based on your task: references/project-setup.md - if starting a new TypeScript library project references/package-exports.md - if configuring package.json exports or dual CJS/ESM references/typescript-config.md - if setting up or modifying tsconfig.json references/build-tooling.md - if configuring tsdown, unbuild, or build scripts references/eslint-config.md - if setting up ESLint for library development references/api-design.md - if designing public APIs, builder patterns, or plugin systems references/type-patterns.md - if working with advanced TypeScript types or type inference references/testing.md - if setting up vitest or writing tests for library code references/release.md - if configuring release workflow or versioning references/ci-workflows.md - if setting up GitHub Actions or CI/CD pipelines DO NOT load all files at once. Load only what's relevant to your current task. New Library Workflow Create project structure → load references/project-setup.md Configure package.json exports → load references/package-exports.md Set up build with tsdown → load references/build-tooling.md Verify build: pnpm build && pnpm pack --dry-run — check output includes .mjs , .cjs , .d.ts Add tests → load references/testing.md Configure release → load references/release.md Quick Start // package.json (minimal) { "name" : "my-lib" , "type" : "module" , "exports" : { "." : { "import" : "./dist/index.mjs" , "require" : "./dist/index.cjs" } } , "main" : "./dist/index.cjs" , "module" : "./dist/index.mjs" , "types" : "./dist/index.d.ts" , "files" : [ "dist" ] } // tsdown.config.ts import { defineConfig } from 'tsdown' export default defineConfig ({ entry : [ 'src/index.ts' ], format : [ 'esm' , 'cjs' ], dts : true , }) 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