postcss-modules-extract-imports

What is postcss-modules-extract-imports?

The postcss-modules-extract-imports npm package is a PostCSS plugin that helps in transforming CSS modules by extracting all local imports and creating a mapping for them. It is commonly used in a CSS module system where CSS is composed in a modular and reusable way. This plugin processes CSS files and rewrites import statements so that they can be bundled correctly by a module bundler.

What are postcss-modules-extract-imports's main functionalities?

Extracting local imports

This feature allows the plugin to extract local imports from a CSS file. When a CSS class composes from another, this plugin rewrites the import to ensure that the composed class includes the necessary styles from the imported class.

import postcss from 'postcss';
import extractImports from 'postcss-modules-extract-imports';

const css = `.className { color: green; } .anotherClass { composes: className; }`;

postcss([extractImports()])
  .process(css, { from: undefined })
  .then(result => {
    console.log(result.css);
  });

Other packages similar to postcss-modules-extract-imports

postcss-import

postcss-import is a PostCSS plugin that allows you to transform @import rules by inlining content. It is similar to postcss-modules-extract-imports in that it processes imports, but it focuses on inlining the imported content rather than extracting and mapping it for CSS modules.

postcss-easy-import

postcss-easy-import is a wrapper around postcss-import, providing additional features like glob pattern matching and the ability to prefix imports. It simplifies the import process but does not specifically target the CSS modules pattern like postcss-modules-extract-imports.

postcss-advanced-variables

postcss-advanced-variables is a plugin that allows you to use variables, conditionals, and iterators in your CSS. While it does not directly handle imports, it provides a modular approach to CSS that can complement the functionality provided by postcss-modules-extract-imports.

README

CSS Modules: Extract Imports

Transforms:

:local(.continueButton) {
  composes: button from "library/button.css";
  color: green;
}

into:

:import("library/button.css") {
  button: __tmp_487387465fczSDGHSABb;
}
:local(.continueButton) {
  composes: __tmp_487387465fczSDGHSABb;
  color: green;
}

Specification

• Only a certain whitelist of properties are inspected. Currently, that whitelist is ['composes'] alone.
• An extend-import has the following format:

composes: className [... className] from "path/to/file.css",  className [... className], className [... className] from global;

Options

• failOnWrongOrder bool generates exception for unpredictable imports order.

.aa {
  composes: b from "./b.css";
  composes: c from "./c.css";
}

.bb {
  /* "b.css" should be before "c.css" in this case */
  composes: c from "./c.css";
  composes: b from "./b.css";
}

Building

npm install
npm test

• Lines:
• Statements:

License

ISC

With thanks

• Mark Dalgleish
• Tobias Koppers
• Guy Bedford

---

Glen Maddern, 2015.

Changelog

3.1.0 - 2024-04-03

Features

• support multiple composes, i.e. .class { composes: a b, c, e d from global, f g from "./file.css"; }