@parcel/transformer-css

What is @parcel/transformer-css?

@parcel/transformer-css is a plugin for the Parcel bundler that handles CSS transformations. It allows you to process CSS files, including features like CSS modules, PostCSS, and automatic vendor prefixing.

What are @parcel/transformer-css's main functionalities?

CSS Modules

CSS Modules allow you to scope CSS by automatically creating unique class names. This prevents class name collisions in larger projects.

/* styles.module.css */
.button {
  background-color: blue;
  color: white;
}

// index.js
import styles from './styles.module.css';

document.getElementById('myButton').className = styles.button;

PostCSS

PostCSS is a tool for transforming CSS with JavaScript plugins. In this example, Autoprefixer is used to add vendor prefixes to CSS rules.

/* postcss.config.js */
module.exports = {
  plugins: [
    require('autoprefixer')
  ]
};

/* styles.css */
.button {
  display: flex;
}

// index.js
import './styles.css';

Automatic Vendor Prefixing

Automatic vendor prefixing ensures that your CSS works across different browsers by adding necessary vendor prefixes.

/* styles.css */
.button {
  display: flex;
}

// index.js
import './styles.css';

Other packages similar to @parcel/transformer-css

postcss

PostCSS is a tool for transforming CSS with JavaScript plugins. It is highly flexible and can be used for a variety of tasks such as autoprefixing, linting, and minifying CSS. Unlike @parcel/transformer-css, PostCSS is not tied to a specific bundler and can be used with various build tools.

css-loader

css-loader is a webpack loader that allows you to import CSS files into your JavaScript modules. It supports features like CSS Modules and can be combined with other loaders like style-loader to inject CSS into the DOM. While @parcel/transformer-css is specific to Parcel, css-loader is designed for use with webpack.

style-loader

style-loader is another webpack loader that injects CSS into the DOM. It is often used in conjunction with css-loader to handle CSS imports in JavaScript files. Unlike @parcel/transformer-css, which is a single package for Parcel, style-loader is part of a modular system in webpack.

README

The README file is missing

Changelog

[2.15.3] – 2025-06-20

Fixed

• JavaScript

  • Expose line and column number to macros – Details

• React Server Components

  • Invalidate cache in ReactStaticPackager when pages are added or client components change – Details
  • Fix lazy mode with React Server Components – Details
  • Fix @parcel/rsc duplicate types – Details
  • Ensure publicUrl ends with a slash in react-static packager – Details
  • Fix hash reference replacement in react-static packager – Details