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Jason Woltje f5792c40be feat: Complete fleet — 94 skills across 10+ domains

Pulled ALL skills from 15 source repositories:
- anthropics/skills: 16 (docs, design, MCP, testing)
- obra/superpowers: 14 (TDD, debugging, agents, planning)
- coreyhaines31/marketingskills: 25 (marketing, CRO, SEO, growth)
- better-auth/skills: 5 (auth patterns)
- vercel-labs/agent-skills: 5 (React, design, Vercel)
- antfu/skills: 16 (Vue, Vite, Vitest, pnpm, Turborepo)
- Plus 13 individual skills from various repos

Mosaic Stack is not limited to coding — the Orchestrator and
subagents serve coding, business, design, marketing, writing,
logistics, analysis, and more.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2026-02-16 16:27:42 -06:00

3.4 KiB

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Output Format

Configure the module format(s) for generated bundles.

Overview

tsdown can generate bundles in multiple formats. Default is ESM.

Available Formats

Format	Description	Use Case
`esm`	ECMAScript Module (default)	Modern Node.js, browsers, Deno
`cjs`	CommonJS	Legacy Node.js, require()
`iife`	Immediately Invoked Function Expression	Browser `<script>` tags
`umd`	Universal Module Definition	AMD, CommonJS, and globals

Usage

CLI

# Single format
tsdown --format esm

# Multiple formats
tsdown --format esm --format cjs

# Or comma-separated
tsdown --format esm,cjs

Config File

Single Format

export default defineConfig({
  entry: ['src/index.ts'],
  format: 'esm',
})

Multiple Formats

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm', 'cjs'],
})

Per-Format Configuration

Override options for specific formats:

export default defineConfig({
  entry: ['src/index.ts'],
  format: {
    esm: {
      target: ['es2015'],
    },
    cjs: {
      target: ['node20'],
    },
  },
})

This allows different targets, platforms, or other settings per format.

Common Patterns

Modern Library (ESM + CJS)

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm', 'cjs'],
  dts: true,
})

Output:

dist/index.mjs (ESM)
dist/index.cjs (CJS)
dist/index.d.ts (Types)

Browser Library (IIFE)

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['iife'],
  globalName: 'MyLib',
  platform: 'browser',
  minify: true,
})

Output: dist/index.global.js (IIFE with global MyLib)

Universal Library (UMD)

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['umd'],
  globalName: 'MyLib',
  platform: 'neutral',
})

Works with AMD, CommonJS, and browser globals.

Node.js Package (CJS + ESM)

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm', 'cjs'],
  platform: 'node',
  dts: true,
  shims: true, // Add __dirname, __filename for CJS compat
})

Framework Component Library

export default defineConfig({
  entry: ['src/index.tsx'],
  format: ['esm', 'cjs'],
  external: ['react', 'react-dom'], // Don't bundle dependencies
  dts: true,
})

Format-Specific Outputs

File Extensions

Format	Extension
ESM	`.mjs` or `.js` (with `"type": "module"`)
CJS	`.cjs` or `.js` (without `"type": "module"`)
IIFE	`.global.js`
UMD	`.umd.js`

Customize Extensions

Use outExtensions to override:

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm', 'cjs'],
  outExtensions: ({ format }) => ({
    js: format === 'esm' ? '.js' : '.cjs',
  }),
})

Tips

Use ESM + CJS for maximum compatibility
Use IIFE for browser-only libraries
Use UMD for universal compatibility (less common now)
Externalize dependencies to avoid bundling framework code
Add shims for CJS compatibility when using Node.js APIs
Set globalName for IIFE/UMD formats

Target - Set JavaScript version
Platform - Set platform (node, browser, neutral)
Shims - Add ESM/CJS compatibility
Output Directory - Customize output paths

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