unplugin-macros

Macros are a mechanism for running JavaScript functions at bundle-time. The value returned from these functions or variables are directly inlined into your bundle.

Installation

# npm
npm i -D unplugin-macros

# jsr
npx jsr add -D @unplugin/macros

// vite.config.ts
import Macros from 'unplugin-macros/vite'

export default defineConfig({
  plugins: [Macros()],
})

// rollup.config.js
import Macros from 'unplugin-macros/rollup'

export default {
  plugins: [Macros()],
}

Requires esbuild >= 0.15

// esbuild.config.js
import { build } from 'esbuild'

build({
  plugins: [require('unplugin-macros/esbuild')()],
})

// webpack.config.js
module.exports = {
  /* ... */
  plugins: [require('unplugin-macros/webpack')()],
}

Usage

// main.js
import { buildTime, getRandom } from './macros' with { type: 'macro' }

getRandom() // Will be replaced with a random number at build time
buildTime // Will be replaced with the timestamp at the build time

// macros.js
export function getRandom() {
  return Math.random()
}
export const buildTime = Date.now()

Function Arguments

You can pass function values as arguments to macros. Functions must be isolated (no references to outside identifiers):

// main.js
import { transform } from './macros' with { type: 'macro' }

transform(() => 42)
transform(async () => await Promise.resolve(42))

See more in Bun Macros.

TypeScript

Import Attributes syntax is supported in TypeScript 5.3 and above.

ESLint

Import Attributes syntax is supported in ESLint v9.14.0.

Options

Refer to docs.

Thanks

Thanks to Bun Macros.

Sponsors

License

MIT License © 2023-PRESENT Kevin Deng