rollup-plugin-thunder

2.0.1 verified Mon Apr 27 auth: no javascript

A Rollup plugin for LightningCSS, providing CSS transformation, minification, and module support. Current stable version 2.0.1 (September 2025) with regular updates. Key differentiators: seamless integration with Rollup, auto CSS modules via naming conventions, and support for CSSStyleSheet. ESM-only, TypeScript-friendly with bundled types.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module not supported. ↓

cause Using CommonJS require() to import an ESM-only package.

fix

Use dynamic import: const thunder = await import('rollup-plugin-thunder');

error Module '"rollup-plugin-thunder"' has no exported member 'classes'. ↓

cause Named export 'classes' was renamed to 'clasess' in v2.0.0.

fix

Use 'clasess' or 'C' instead of 'classes'.

error TypeError: thunder is not a function ↓

cause Default import used as function but imported as named export.

fix

Use default import: import thunder from 'rollup-plugin-thunder'

Warnings

breaking Export class list as `clasess` and shorthand `C` named export. Previous `classes` export removed. ↓

fix Change imports to use 'clasess' or 'C' instead of 'classes'.

deprecated Options may change in future minor versions without major semver bump. ↓

fix Pin exact version and review changelog for option changes.

gotcha The 'clasess' export name is intentionally misspelled. Expect typos in user code. ↓

fix Use correct spelling 'clasess' or shorthand 'C'.

gotcha Plugin is ESM-only. CommonJS require() throws error. ↓

fix Use dynamic import or ensure project is ESM.

gotcha CSS modules auto-detection may conflict with other CSS plugins (e.g., postcss). ↓

fix Disable 'autoModules' or customize regex to avoid overlap.

Install

npm install rollup-plugin-thunder

yarn add rollup-plugin-thunder

pnpm add rollup-plugin-thunder

Imports

thunder

wrong

const thunder = require('rollup-plugin-thunder')

correct

import thunder from 'rollup-plugin-thunder'

Default import. CommonJS require will fail; ESM-only since v1.

clasess
wrong
```
import { classes } from 'rollup-plugin-thunder'
```
correct
```
import { clasess } from 'rollup-plugin-thunder'
```
Named export for CSS class list. Spelling is intentional: 'clasess' (double s). Breaking change in v2.0.0.
C
```
import { C } from 'rollup-plugin-thunder'
```
Shorthand named export for clasess (available since v2.0.0).

type Options

wrong

import { Options } from 'rollup-plugin-thunder'

correct

import type { Options } from 'rollup-plugin-thunder'

Type import for TypeScript users. Only available as type, not runtime value.

Quickstart

Configures Rollup with Thunder plugin for CSS processing: minification, source maps, CSS modules, and auto-module detection.

import thunder from 'rollup-plugin-thunder';

export default {
  input: 'src/index.css',
  plugins: [
    thunder({
      minify: true,
      sourceMap: true,
      modules: true,
      autoModules: /\\.module\\.css$/,
    }),
  ],
  output: {
    dir: 'dist',
    format: 'esm',
  },
};