rollup-copy-transform-css

2.2.0 verified Mon Apr 27 auth: no javascript

Rollup plugin utility for transforming CSS files during copy operations with rollup-plugin-copy. Current stable version is 2.2.0, released November 2025, with support for Rollup 2, 3, and 4. Provides CSS minification via cssnano or esbuild, stylesheet and asset inlining via postcss-import and postcss-url, and custom PostCSS plugin pipelines. Key differentiators: supports both PostCSS and esbuild engines for fast processing, integrates seamlessly with rollup-plugin-copy targets, and offers source map generation. Requires Node.js 18+ as of v2.0.0.

Common errors

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

cause Using require() on this package which is ESM-only since v2

fix

Use dynamic import: const { createTransform } = await import('rollup-copy-transform-css');

error TypeError: createTransform is not a function ↓

cause Importing default export incorrectly instead of named export createTransform

fix

Use import { createTransform } from 'rollup-copy-transform-css'

error Error: rollup-plugin-copy is not installed ↓

cause Missing required peer dependency rollup-plugin-copy

fix

Install rollup-plugin-copy alongside this package: npm i -D rollup-plugin-copy

Warnings

breaking Node.js 18 is required ↓

fix Upgrade Node.js to version 18 or later

breaking ESM-only: no CommonJS support ↓

fix Use import syntax instead of require; set type: 'module' in package.json

gotcha Experimental esbuild engine may produce different output than PostCSS ↓

fix Set minify: { fast: true } or inline: { fast: true } to use esbuild; test output carefully

gotcha Source map generation may be silently ignored if not explicitly configured ↓

fix Ensure map option is set to boolean or object in createTransform or transform call

Install

npm install rollup-copy-transform-css

yarn add rollup-copy-transform-css

pnpm add rollup-copy-transform-css

Imports

createTransform

wrong

const { createTransform } = require('rollup-copy-transform-css')

correct

import { createTransform } from 'rollup-copy-transform-css'

ESM-only since v2; CJS require may fail or produce undefined

default

wrong

import createTransform from 'rollup-copy-transform-css'

correct

import { createTransform } from 'rollup-copy-transform-css'

No default export; only named export createTransform is available

copy plugin

wrong

import { copy } from 'rollup-plugin-copy'

correct

import copy from 'rollup-plugin-copy'

rollup-plugin-copy uses default export

Quickstart

Basic Rollup config using rollup-plugin-copy with transform that minifies CSS and generates an external source map.

import copy from 'rollup-plugin-copy';
import { createTransform } from 'rollup-copy-transform-css';

const transformCss = createTransform({
  inline: false,
  minify: true,
  map: { inline: false }
});

export default {
  input: 'src/index.js',
  output: {
    file: 'dist/bundle.js',
    format: 'iife'
  },
  plugins: [
    copy({
      targets: [
        {
          src: 'src/styles/main.css',
          dest: 'dist/styles',
          transform: transformCss
        }
      ]
    })
  ]
};