unplugin-parcel-macros

0.2.0 verified Mon Apr 27 auth: no javascript

Unplugin plugin that brings Parcel's macro system to webpack, Vite, Rollup, esbuild, Next.js, and more. Macros are JavaScript/TypeScript functions that execute at build time, returning values that get inlined into the bundle, enabling compile-time computation, code generation, and asset creation without custom plugins. Version 0.2.0, actively maintained, requires Node >= 18 and an import attribute (with {type: 'macro'}). Compared to babel macros or webpack loader-based approaches, it leverages Unplugin for universal integration and follows the TC39 import attributes proposal.

Common errors

error Error: require() of ES Module not supported ↓

cause Using require() to import the ESM-only package

fix

Use import syntax or convert your project to ESM (type:'module' in package.json).

error Missing: with {type: 'macro'} - Unexpected token ↓

cause The import attribute syntax is not parsed by the current bundler/transpiler

fix

Use a tool that supports import attributes (e.g., Node >= 18, modern bundlers) or transpile with SWC/Babel plugin.

error Error: Cannot find module 'unplugin-parcel-macros' ↓

cause Package not installed

fix

Run npm install unplugin-parcel-macros --save-dev

Warnings

gotcha Import attributes syntax (with {type: 'macro'}) is not supported in older bundlers or Node versions without transpilation. ↓

fix Ensure your toolchain supports the syntax or use a transpiler like SWC or Babel that strips the attribute.

breaking Macros must be imported with the exact attribute with {type: 'macro'}. Using a non-standard syntax like assert {type: 'macro'} will not work. ↓

fix Use with {type: 'macro'} as per the import attributes proposal.

gotcha The macro module is executed at build time and cannot access runtime variables from the calling module. ↓

fix Ensure macro arguments are compile-time constants or expressions evaluable at build time.

deprecated Import attributes are still a Stage 3 proposal and may change in the future. ↓

fix Keep the library updated to adapt to spec changes.

Install

npm install unplugin-parcel-macros

yarn add unplugin-parcel-macros

pnpm add unplugin-parcel-macros

Imports

default
wrong
```
const macros = require('unplugin-parcel-macros')
```
correct
```
import macros from 'unplugin-parcel-macros'
```
ESM-only; default export is an object with .webpack(), .vite(), .rollup(), .esbuild() methods.
webpack
wrong
```
macros.webpack
```
correct
```
macros.webpack()
```
Call the method to get the plugin instance. Used in both plain Webpack and Next.js.
vite
wrong
```
macros.vite
```
correct
```
macros.vite()
```
Call the method to get the Vite plugin.

Quickstart

Shows how to add the Vite plugin and use a macro with the import attribute to generate a regex at build time.

// vite.config.js
import macros from 'unplugin-parcel-macros';
import { defineConfig } from 'vite';

export default defineConfig({
  plugins: [
    macros.vite()
  ]
});

// src/index.js
import regexgen from 'regexgen' with { type: 'macro' };
const regex = regexgen(['foo', 'bar', 'baz']);
export default regex;