Migrating to bunchee 7

Requirements

bunchee 7 requires Node.js 22.12 or newer. Its default JavaScript target is now ES2022; pass --target or configure compilerOptions.target when an older output target is required.

TypeScript 5 and 6 continue to work as before. TypeScript 7 no longer exposes the JavaScript compiler API bunchee uses to emit declarations, so TypeScript 7 projects must also install its official compatibility package:

npm install --save-dev @typescript/typescript6

ESM defaults

The bunchee package itself is now ESM. Replace CommonJS loading of its Node.js API with an ESM import:

-const { bundle } = require('bunchee')
+import { bundle } from 'bunchee'

bunchee prepare now generates an ESM-only package by default. Pass --cjs when generating both ESM and CommonJS exports:

bunchee prepare --cjs

The old --prepare build flag has been removed; use the bunchee prepare command explicitly.

Package metadata

Newly prepared packages no longer receive a legacy module field. Prefer the standard exports field, with main and types only when compatibility with older resolvers is needed.

TypeScript still supports typings as a legacy alias for types, but bunchee 7 no longer reads it as the package-level declaration target. Rename it to types, or add a types export condition:

-"typings": "./dist/index.d.ts"
+"types": "./dist/index.d.ts"

Output chunks

bunchee 7 builds entries through a shared module graph. This avoids rebuilding common modules, improves declaration performance, and keeps directive layers such as use client, use server, and use cache separate. Packages that inspect generated chunk names should treat those names as build artifacts and update any snapshots after migrating.