tsdown

# tsdown - The Elegant Library Bundler Blazing-fast bundler for TypeScript/JavaScript libraries powered by Rolldown and Oxc. ## Runtime Requirement `tsdown` requires **Node.js 22.18.0 or higher to run** (build-time only). However, the bundled output can target much lower Node.js versions via the [`target`](references/option-target.md) option, so libraries built with tsdown are **not locked to Node.js 22+ at runtime**. If your package needs to support Node.js 18 / 20: - **Build with Node.js 22+ in CI** (e.g. set `target: 'node18'` or `target: 'node20'`). - **Test the built output (or the packed tarball) on the lower Node.js versions** you intend to support — e.g. using a matrix job that runs the published package's tests on Node.js 18 / 20 / 22. ## When to Use - Building TypeScript/JavaScript libraries for npm - Generating TypeScript declaration files (.d.ts) - Bundling for multiple formats (ESM, CJS, IIFE, UMD) - Optimizing bundles with tree shaking and minification - Migrating from tsup with minimal changes - Building React, Vue, Solid, or Svelte component libraries ## Quick Start ```bash # Install pnpm add -D tsdown # Basic usage npx tsdown # With config file npx tsdown --config tsdown.config.ts # Watch mode npx tsdown --watch # Migrate from tsup npx tsdown-migrate ``` ## Basic Configuration ```ts import { defineConfig } from 'tsdown' export default defineConfig({ entry: ['./src/index.ts'], format: ['esm', 'cjs'], dts: true, clean: true, }) ``` ## Core References | Topic | Description | Reference | |-------|-------------|-----------| | Getting Started | Installation, first bundle, CLI basics | [guide-getting-started](references/guide-getting-started.md) | | Configuration File | Config file formats, multiple configs, workspace | [option-config-file](references/option-config-file.md) | | CLI Reference | All CLI commands and options | [reference-cli](references/reference-cli.md) | | Migrate from tsup | Migration guide and compatibility notes | [guide-migrate-from-tsup](references/guide-migrate-from-tsup.md) | | Plugins | Rolldown, Rollup, Unplugin support | [advanced-plugins](references/advanced-plugins.md) | | Hooks | Lifecycle hooks for custom logic | [advanced-hooks](references/advanced-hooks.md) | | Programmatic API | Build from Node.js scripts, in-memory builds (`write: false`) | [advanced-programmatic](references/advanced-programmatic.md) | | Rolldown Options | Pass options directly to Rolldown | [advanced-rolldown-options](references/advanced-rolldown-options.md) | | CI Environment | CI detection, `'ci-only'` / `'local-only'` values | [advanced-ci](references/advanced-ci.md) | > For comprehensive migration assistance with complete option mappings, install the dedicated [`tsdown-migrate`](../tsdown-migrate/SKILL.md) skill: `npx skills add rolldown/tsdown --skill tsdown-migrate` ## Build Options | Option | Usage | Reference | |--------|-------|-----------| | Entry points | `entry: ['src/*.ts', '!**/*.test.ts']` | [option-entry](references/option-entry.md) | | Output formats | `format: ['esm', 'cjs', 'iife', 'umd']` | [option-output-format](references/option-output-format.md) | | Output directory | `outDir: 'dist'`, `outExtensions` | [option-output-directory](references/option-output-directory.md) | | Type declarations | `dts: true`, `dts: { sourcemap, compilerOptions, vue }` | [option-dts](references/option-dts.md) | | Target environment | `target: 'es2020'`, `target: 'esnext'` | [option-target](references/option-target.md) | | Platform | `platform: 'node'`, `platform: 'browser'` | [option-platform](references/option-platform.md) | | Tree shaking | `treeshake: true`, custom options | [option-tree-shaking](references/option-tree-shaking.md) | | Minification | `minify: true`, `minify: 'dce-only'` | [option-minification](references/option-minification.md) | | Source maps | `sourcemap: true`, `'inline'`, `'hidden'` | [option-sourcemap](references/option-sourcemap.md) | | Watch mode | `watch: true`, watch options | [option-watch-mode](references/option-watch-mode.md) | | Cleaning | `clean: true`, clean patterns | [option-cleaning](references/option-cleaning.md) | | Log level | `logLevel: 'silent'`, `failOnWarn: false`, `suppressWarnings: [...]` | [option-log-level](references/option-log-level.md) | ## Dependency Handling | Feature | Usage | Reference | |---------|-------|-----------| | Never bundle | `deps: { neverBundle: ['react', /^@myorg\//] }` | [option-dependencies](references/option-dependencies.md) | | Always bundle | `deps: { alwaysBundle: ['dep-to-bundle'] }` | [option-dependencies](references/option-dependencies.md) | | Only bundle | `deps: { onlyBundle: ['cac', 'bumpp'] }` - Whitelist | [option-dependencies](references/option-dependencies.md) | | Only import | `deps: { onlyImport: ['cac'] }` - Whitelist runtime imports in output | [option-dependencies](references/option-dependencies.md) | | Externalize all | `deps: { neverBundle: true }` | [option-dependencies](references/option-dependencies.md) | | Resolve subpaths | `deps: { resolveDepSubpath: true }` - Resolve external subpath imports (default `false`) | [option-dependencies](references/option-dependencies.md) | | Auto external | Automatic dependency/peer/optional externalization | [option-dependencies](references/option-dependencies.md) | ## Output Enhancement | Feature | Usage | Reference | |---------|-------|-----------| | Shims | `shims: true` - Add ESM/CJS compatibility | [option-shims](references/option-shims.md) | | CJS default | `cjsDefault: true` (default) / `false` | [option-cjs-default](references/option-cjs-default.md) | | Package exports | `exports: true` - Generate exports field | [option-package-exports](references/option-package-exports.md) | | CSS handling | **[experimental]** `css: { ... }` — full pipeline with preprocessors, Lightning CSS, PostCSS, CSS modules, code splitting; requires `@tsdown/css` | [option-css](references/option-css.md) | | CSS modules | `css: { modules: { localsConvention: 'camelCase' } }` — scoped class names for `.module.css` files | [option-css](references/option-css.md) | | CSS inject | `css: { inject: true }` — preserve CSS imports in JS output | [option-css](references/option-css.md) | | Copy files | `copy: 'public'` or `copy: { from, to, flatten, rename }` - Copy static assets to output | [option-copy](references/option-copy.md) | | Unbundle mode | `unbundle: true` - Preserve directory structure | [option-unbundle](references/option-unbundle.md) | | Root directory | `root: 'src'` - Control output directory mapping | [option-root](references/option-root.md) | | Executable | **[experimental]** `exe: true` - Bundle as standalone executable, cross-platform via `@tsdown/exe` | [option-exe](references/option-exe.md) | | Package validation | `publint: true`, `attw: true` - Validate package | [option-lint](references/option-lint.md) | ## Framework & Runtime Support | Framework | Guide | Reference | |-----------|-------|-----------| | React | JSX transform, React Compiler | [recipe-react](references/recipe-react.md) | | Vue | SFC support, JSX | [recipe-vue](references/recipe-vue.md) | | Solid | SolidJS JSX transform | [recipe-solid](references/recipe-solid.md) | | Svelte | Svelte component libraries (source distribution recommended) | [recipe-svelte](references/recipe-svelte.md) | | WASM | WebAssembly modules via `rolldown-plugin-wasm` | [recipe-wasm](references/recipe-wasm.md) | ## Common Patterns ### Basic Library Bundle ```ts export default defineConfig({ entry: ['src/index.ts'], format: ['esm', 'cjs'], dts: true, clean: true, }) ``` ### Multiple Entry Points ```ts export default defineConfig({ entry: { index: 'src/index.ts', utils: 'src/utils.ts', cli: 'src/cli.ts', }, format: ['esm', 'cjs'], dts: true, }) ``` ### Browser Library (IIFE/UMD) ```ts export default defineConfig({ entry: ['src/index.ts'], format: ['iife'], globalName: 'MyLib', platform: 'browser', minify: true, }) ``` ### React Component Library ```ts export default defineConfig({ entry: ['src/index.tsx'], format: ['esm', 'cjs'], dts: true, deps: { neverBundle: ['react', 'react-dom'], }, inputOptions: { jsx: { runtime: 'automatic' }, }, }) ``` ### Preserve Directory Structure ```ts export default defineConfig({ entry: ['src/**/*.ts', '!**/*.test.ts'], unbundle: true, // Preserve file structure format: ['esm'], dts: true, }) ``` ### CI-Aware Configuration ```ts export default defineConfig({ entry: ['src/index.ts'], format: ['esm', 'cjs'], dts: true, failOnWarn: 'ci-only', // opt-in: fail on warnings in CI publint: 'ci-only', attw: 'ci-only', }) ``` ### WASM Support ```ts import { wasm } from 'rolldown-plugin-wasm' import { defineConfig } from 'tsdown' export default defineConfig({ entry: ['src/index.ts'], plugins: [wasm()], }) ``` ### Library with CSS and Sass ```ts export default defineConfig({ entry: ['src/index.ts'], format: ['esm', 'cjs'], dts: true, target: 'chrome100', css: { preprocessorOptions: { scss: { additionalData: `@use "src/styles/variables" as *;`, }, }, }, }) ``` ### Standalone Executable ```ts export default defineConfig({ entry: ['src/cli.ts'], exe: true, }) ``` ### Cross-Platform Executable (requires `@tsdown/exe`) ```ts export default defineConfig({ entry: ['src/cli.ts'], exe: { targets: [ { platform: 'linux', arch: 'x64', nodeVersion: '25.7.0' }, { platform: 'darwin', arch: 'arm64', nodeVersion: '25.7.0' }, { platform: 'win', arch: 'x64', nodeVersion: '25.7.0' }, ],