bunchee

zero config bundler for JavaScript/TypeScript/JSX library

Bunchee makes bundling your library into one file effortless, with zero configuration required. It is built on top of Rollup and SWC ⚡️, allowing you to focus on writing code and generating multiple module types (CommonJS, ESModules) simultaneously.

Installation

npm install --save-dev bunchee

Usage

Package.json Configuration

Declare the main and module fields in your package.json file, then call the bunchee CLI in the build scripts. If you are using TypeScript, types will be generated automatically based on the typings or types field in your package.json file.

Configure main and module fields

You can have Commonjs + ESModules output as the simple config

{
  "main": "dist/pkg.cjs.js",
  "module": "dist/pkg.esm.js",
  "scripts": {
    "build": "bunchee ./src/index.js"
  },
  "types": "dist/types/index.d.ts"
}

Configure exports field

exports sugar in Node.js

You can use the exports field to support different conditions and leverage the same functionality as other bundlers, such as webpack. The exports field allows you to define multiple conditions.

{
  "exports": {
    "require": "dist/index.cjs",
    "import": "dist/index.mjs",
    "module": "dist/index.esm.js"
  },
  "scripts": {
    "build": "bunchee ./src/index.js"
  },
}

CLI

Usage: bunchee [options]

Options:
  -v, --version          output the version number
  -w, --watch            watch src files changes
  -m, --minify           compress output. default: false
  -o, --output <file>    specify output filename
  -f, --format <format>  type of output (esm, amd, cjs, iife, umd, system), default: esm
  -e, --external <mod>   specify an external dependency
  -h, --help             output usage information
  --target <target>      js features target: swc target es versions. default: es2015
  --runtime <runtime>    build runtime (nodejs, browser). default: browser
  --cwd <cwd>            specify current working directory
  --sourcemap            enable sourcemap generation, default: false
  --dts                  determine if need to generate types, default: false

Usage:
  $ bunchee ./src/index.js # if you set main fields in package.json
  $ bunchee ./src/index.ts -o ./dist/bundle.js # specify the dist file path

Run bunchee via CLI

cd <project-root-dir>
bunchee ./src/index.js -f cjs -o ./dist/bundle.js

bunchee ./src/index.js -f esm -o ./dist/bundle.esm.js
# if you don't specify format type, default format is ESModule
# bunchee ./src/index.js -o ./dist/bundle.esm.js

Node.js API

import path from 'path'
import { bundle } from 'bunchee'

// The definition of these options can be found in help information
await bundle(path.resolve('./src/index.ts'), {
  dts: false,
  watch: false,
  minify: false,
  sourcemap: false,
  external: [],
  format: 'esm',
  target: 'es2016',
  runtime: 'nodejs',
})

Watch Mode

Bunchee offers a convenient watch mode for rebuilding your library whenever changes are made to the source files. To enable this feature, use either -w or --watch.

Typescript

By default bunchee includes Typescript v3.9.x inside as a dependency. If you want to use your own version, just install typescript as another dev dependency then bunchee will automatically pick it.

yarn add -D bunchee typescript

Create tsconfig.json to specify any compiler options for TypeScript.

This library requires at least TypeScript 3.7.

target

If you specify target option in tsconfig.json, then you don't have to pass it again through CLI.

Advanced

Multiple Exports

While exports filed is becoming the standard of exporting in node.js, bunchee also supports to build multiple exports all in one command.

What you need to do is just add an entry file with the name ([name].[ext]) that matches the exported name from exports field in package.json. For instance:

• index.ts will match "." export name or the if there's only one main export.
• lite.ts will match "./lite" export name.

The build script will be simplified to just bunchee in package.json without configure any input sources for each exports. Of course you can still specify other arguments as you need.

How it works

Assuming you have main entry export "." and subpath export "./lite" with different exports condition listed in package.json

{
  "name": "example",
  "scripts": {
     "build": "bunchee"
  },
  "exports": {
    "./lite": "./dist/lite.js"
    ".": {
      "import": "./dist/index.mjs",
      "require": "./dist/index.cjs"
   }
  }
}

Then you need to add two entry files index.ts and lite.ts in project root directory to match the export name "." and "./lite", bunchee will associate these entry files with export names then use them as input source and output paths information.

- example/
  |- lite.ts
  |- index.ts
  |- src/
  |- package.json

License

MIT