postcss-modules-scope

What is postcss-modules-scope?

The postcss-modules-scope npm package is a PostCSS plugin that helps in locally scoping CSS by automatically renaming classes and other identifiers to be unique. This ensures that styles do not conflict across different parts of an application. It is commonly used in modular CSS architecture.

What are postcss-modules-scope's main functionalities?

Local Scoping of CSS Classes

This feature automatically renames CSS classes to include a unique identifier, preventing class name collisions.

/* Input CSS */
.className {
  color: red;
}

/* Output CSS after processing with postcss-modules-scope */
._className_1a2b3c {
  color: red;
}

Renaming of Animation Names

This feature renames animation names with a unique identifier to avoid conflicts with other animations in the global scope.

/* Input CSS */
@keyframes myAnimation {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Output CSS after processing with postcss-modules-scope */
@keyframes myAnimation_1a2b3c {
  from { opacity: 0; }
  to { opacity: 1; }
}

Other packages similar to postcss-modules-scope

css-loader

css-loader is a webpack loader that interprets `@import` and `url()` like `import/require()` and will resolve them. It also offers modules functionality that allows for local scoping of CSS by default, similar to what postcss-modules-scope provides.

postcss-modules

postcss-modules is another PostCSS plugin that goes beyond scoping and also tracks the CSS dependencies and exports the generated identifiers. It provides a more integrated solution for working with CSS modules.

postcss-preset-env

postcss-preset-env is a plugin that allows you to use future CSS features today. It includes cssdb-compliant plugins that convert modern CSS into something most browsers can understand, ensuring that features are only polyfilled as needed. It doesn't provide CSS modules functionality directly but can be used in conjunction with other modules plugins.

README

CSS Modules: Scope Locals & Extend

Transforms:

:local(.continueButton) {
  color: green;
}

into:

:export {
  continueButton: __buttons_continueButton_djd347adcxz9;
}
.__buttons_continueButton_djd347adcxz9 {
  color: green;
}

so it doesn't pollute CSS global scope and can be simply used in JS like so:

import styles from "./buttons.css";
elem.innerHTML = `<button class="${styles.continueButton}">Continue</button>`;

Composition

Since we're exporting class names, there's no reason to export only one. This can give us some really useful reuse of styles:

.globalButtonStyle {
  background: white;
  border: 1px solid;
  border-radius: 0.25rem;
}
.globalButtonStyle:hover {
  box-shadow: 0 0 4px -2px;
}
:local(.continueButton) {
  compose-with: globalButtonStyle;
  color: green;
}

becomes:

.globalButtonStyle {
  background: white;
  border: 1px solid;
  border-radius: 0.25rem;
}
.globalButtonStyle:hover {
  box-shadow: 0 0 4px -2px;
}
:local(.continueButton) {
  compose-with: globalButtonStyle;
  color: green;
}

Note: you can also use composes as a shorthand for compose-with

Local-by-default & reuse across files

You're looking for CSS Modules. It uses this plugin as well as a few others, and it's amazing.

Building

npm install
npm test

• Status:
• Lines:
• Statements:

Development

• npm test:watch will watch src and test for changes and run the tests

License

ISC

With thanks

• Mark Dalgleish
• Tobias Koppers
• Guy Bedford

---

Glen Maddern, 2015.

Changelog

3.2.1

Chore

• update postcss-selector-parser