xingyu4j tsdown - The Elegant Library Bundler
Blazing-fast bundler for TypeScript/JavaScript libraries powered by Rolldown and Oxc.
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
# 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
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 |
| Configuration File | Config file formats, multiple configs, workspace | option-config-file |
| CLI Reference | All CLI commands and options | reference-cli |
| Migrate from tsup | Migration guide and compatibility notes | guide-migrate-from-tsup |
| Plugins | Rolldown, Rollup, Unplugin support | advanced-plugins |
| Hooks | Lifecycle hooks for custom logic | advanced-hooks |
| Programmatic API | Build from Node.js scripts | advanced-programmatic |
| Rolldown Options | Pass options directly to Rolldown | advanced-rolldown-options |
| CI Environment | CI detection, 'ci-only' / 'local-only' values |
advanced-ci |
Build Options
| Option | Usage | Reference |
|---|---|---|
| Entry points | entry: ['src/*.ts', '!**/*.test.ts'] |
option-entry |
| Output formats | format: ['esm', 'cjs', 'iife', 'umd'] |
option-output-format |
| Output directory | outDir: 'dist', outExtensions |
option-output-directory |
| Type declarations | dts: true, dts: { sourcemap, compilerOptions, vue } |
option-dts |
| Target environment | target: 'es2020', target: 'esnext' |
option-target |
| Platform | platform: 'node', platform: 'browser' |
option-platform |
| Tree shaking | treeshake: true, custom options |
option-tree-shaking |
| Minification | minify: true, minify: 'dce-only' |
option-minification |
| Source maps | sourcemap: true, 'inline', 'hidden' |
option-sourcemap |
| Watch mode | watch: true, watch options |
option-watch-mode |
| Cleaning | clean: true, clean patterns |
option-cleaning |
| Log level | logLevel: 'silent', failOnWarn: false |
option-log-level |
Dependency Handling
| Feature | Usage | Reference |
|---|---|---|
| Never bundle | deps: { neverBundle: ['react', /^@myorg\//] } |
option-dependencies |
| Always bundle | deps: { alwaysBundle: ['dep-to-bundle'] } |
option-dependencies |
| Only allow bundle | deps: { onlyAllowBundle: ['cac', 'bumpp'] } - Whitelist |
option-dependencies |
| Skip node_modules | deps: { skipNodeModulesBundle: true } |
option-dependencies |
| Auto external | Automatic peer/dependency externalization | option-dependencies |
Output Enhancement
| Feature | Usage | Reference |
|---|---|---|
| Shims | shims: true - Add ESM/CJS compatibility |
option-shims |
| CJS default | cjsDefault: true (default) / false |
option-cjs-default |
| Package exports | exports: true - Auto-generate exports field |
option-package-exports |
| CSS handling | [experimental] Still in development | option-css |
| Unbundle mode | unbundle: true - Preserve directory structure |
option-unbundle |
| Executable (SEA) | [experimental] exe: true - Bundle as Node.js SEA executable |
option-exe |
| Package validation | publint: true, attw: true - Validate package |
option-lint |
Framework & Runtime Support
| Framework | Guide | Reference |
|---|---|---|
| React | JSX transform, Fast Refresh | recipe-react |
| Vue | SFC support, JSX | recipe-vue |
| WASM | WebAssembly modules via rolldown-plugin-wasm |
recipe-wasm |
Common Patterns
Basic Library Bundle
export default defineConfig({
entry: ['src/index.ts'],
format: ['esm', 'cjs'],
dts: true,
clean: true,
})
Multiple Entry Points
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)
export default defineConfig({
entry: ['src/index.ts'],
format: ['iife'],
globalName: 'MyLib',
platform: 'browser',
minify: true,
})
React Component Library
export default defineConfig({
entry: ['src/index.tsx'],
format: ['esm', 'cjs'],
dts: true,
deps: {
neverBundle: ['react', 'react-dom'],
},
plugins: [
// React Fast Refresh support
],
})
Preserve Directory Structure
export default defineConfig({
entry: ['src/**/*.ts', '!**/*.test.ts'],
unbundle: true, // Preserve file structure
format: ['esm'],
dts: true,
})
CI-Aware Configuration
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
import { wasm } from 'rolldown-plugin-wasm'
import { defineConfig } from 'tsdown'
export default defineConfig({
entry: ['src/index.ts'],
plugins: [wasm()],
})
Node.js Executable (SEA)
export default defineConfig({
entry: ['src/cli.ts'],
exe: true,
})
Advanced with Hooks
export default defineConfig({
entry: ['src/index.ts'],
format: ['esm', 'cjs'],
dts: true,
hooks: {
'build:before': async (context) => {
console.log('Building...')
},
'build:done': async (context) => {
console.log('Build complete!')
},
},
})
Configuration Features
Multiple Configs
Export an array for multiple build configurations:
export default defineConfig([
{
entry: ['src/index.ts'],
format: ['esm', 'cjs'],
dts: true,
},
{
entry: ['src/cli.ts'],
format: ['esm'],
platform: 'node',
},
])
Conditional Config
Use functions for dynamic configuration:
export default defineConfig((options) => {
const isDev = options.watch
return {
entry: ['src/index.ts'],
format: ['esm', 'cjs'],
minify: !isDev,
sourcemap: isDev,
}
})
Workspace/Monorepo
Use glob patterns to build multiple packages:
export default defineConfig({
workspace: 'packages/*',
entry: ['src/index.ts'],
format: ['esm', 'cjs'],
dts: true,
})
CLI Quick Reference
# Basic commands
tsdown # Build once
tsdown --watch # Watch mode
tsdown --config custom.ts # Custom config
npx tsdown-migrate # Migrate from tsup
# Output options
tsdown --format esm,cjs # Multiple formats
tsdown --outDir lib # Custom output directory
tsdown --minify # Enable minification
tsdown --dts # Generate declarations
tsdown --exe # Bundle as executable (SEA)
# Entry options
tsdown src/index.ts # Single entry
tsdown src/*.ts # Glob patterns
tsdown src/a.ts src/b.ts # Multiple entries
# Development
tsdown --watch # Watch mode
tsdown --sourcemap # Generate source maps
tsdown --clean # Clean output directory
Best Practices
Always generate type declarations for TypeScript libraries:
{ dts: true }Externalize dependencies to avoid bundling unnecessary code:
{ deps: { neverBundle: [/^react/, /^@myorg\//] } }Use tree shaking for optimal bundle size:
{ treeshake: true }Enable minification for production builds:
{ minify: true }Add shims for better ESM/CJS compatibility:
{ shims: true } // Adds __dirname, __filename, etc.Auto-generate package.json exports:
{ exports: true } // Creates proper exports fieldUse watch mode during development:
tsdown --watchPreserve structure for utilities with many files:
{ unbundle: true } // Keep directory structureValidate packages in CI before publishing:
{ publint: 'ci-only', attw: 'ci-only' }
Resources
- Documentation: https://tsdown.dev
- GitHub: https://github.com/rolldown/tsdown
- Rolldown: https://rolldown.rs
- Migration Guide: https://tsdown.dev/guide/migrate-from-tsup