@rolldown/plugin-emotion

Rolldown plugin for minification and optimization of Emotion styles.

This plugin utilizes Rolldown's native magic string API instead of Babel and is more performant than using @emotion/babel-plugin with @rolldown/plugin-babel.

Install

pnpm add -D @rolldown/plugin-emotion

Usage

import emotion from '@rolldown/plugin-emotion'

export default {
  plugins: [
    emotion({
      // options
    }),
  ],
}

Supported Libraries

The plugin handles imports from these Emotion packages out of the box:

• @emotion/css
• @emotion/styled
• @emotion/react
• @emotion/primitives
• @emotion/native

Options

sourceMap

• Type: boolean
• Default: true in development, false otherwise

Generate source maps for Emotion CSS. Source maps help trace styles back to their original source in browser DevTools.

autoLabel

• Type: 'never' | 'dev-only' | 'always'
• Default: 'dev-only'

Controls when debug labels are added to styled components and css calls.

• 'never' — Never add labels
• 'dev-only' — Only add labels in development mode
• 'always' — Always add labels

labelFormat

• Type: string
• Default: "[local]"

Defines the format of generated debug labels. Only relevant when autoLabel is not 'never'.

Supports placeholders:

• [local] — The variable name that the result of css or styled call is assigned to
• [filename] — The file name (without extension)
• [dirname] — The directory name of the file

emotion({
  autoLabel: 'always',
  labelFormat: '[dirname]--[filename]--[local]',
})

importMap

• Type: Record<string, ImportMapConfig>

Custom import mappings for non-standard Emotion packages. Maps package names to their export configurations, allowing the plugin to transform custom libraries that re-export Emotion utilities.

emotion({
  importMap: {
    'my-emotion-lib': {
      myStyled: {
        canonicalImport: ['@emotion/styled', 'default'],
      },
      myCss: {
        canonicalImport: ['@emotion/react', 'css'],
      },
    },
  },
})

Each entry maps an export name to its canonical Emotion equivalent via canonicalImport: [packageName, exportName].

Benchmark

Results of the benchmark that can be run by pnpm bench in ./benchmark directory:

  name                          hz      min     max    mean     p75     p99    p995    p999     rme  samples
· @rolldown/plugin-emotion  9.7954  98.4954  108.83  102.09  103.34  108.83  108.83  108.83  ±2.23%       10
· @rolldown/plugin-babel    3.7139   254.48  295.01  269.26  277.63  295.01  295.01  295.01  ±3.49%       10
· @rollup/plugin-swc        7.5542   128.56  139.14  132.38  134.82  139.14  139.14  139.14  ±1.78%       10

@rolldown/plugin-emotion - bench/emotion.bench.ts > Emotion Benchmark
  1.30x faster than @rollup/plugin-swc
  2.64x faster than @rolldown/plugin-babel

The benchmark was ran on the following environment:

OS: macOS Tahoe 26.3
CPU: Apple M4
Memory: LPDDR5X-7500 32GB

License

MIT

Credits

The implementation is based on swc-project/plugins/packages/emotion (Apache License 2.0). Test cases are also adapted from it.