icss-utils

What is icss-utils?

The icss-utils package provides utilities for working with ICSS (Interoperable CSS), which is a convention for handling CSS modules. It allows for the extraction and manipulation of CSS module content, such as importing/exporting variables and handling scoped CSS.

What are icss-utils's main functionalities?

Extracting ICSS imports and exports

This feature allows you to extract ICSS imports and exports from a CSS string. The `extractICSS` function returns an object with `icssImports` and `icssExports` properties, which contain the extracted values.

const { extractICSS } = require('icss-utils');
const css = ':export { color: red; }';
const { icssImports, icssExports } = extractICSS(css);

Replacing values in CSS

This feature enables you to replace symbols in a CSS string with specified values. The `replaceSymbols` function takes a CSS string and an object of replacements, then returns the CSS with the values replaced.

const { replaceSymbols } = require('icss-utils');
const css = '.className { color: colorValue; }';
const replacements = { colorValue: 'red' };
const result = replaceSymbols(css, replacements);

Creating an ICSS replacement map

This feature helps in creating a map of ICSS replacements from exports. The `createICSSReplacements` function takes an object of ICSS exports and returns an object that can be used for replacing symbols in CSS.

const { createICSSReplacements } = require('icss-utils');
const icssExports = { color: 'red' };
const replacements = createICSSReplacements(icssExports);

Other packages similar to icss-utils

postcss-modules

This package is a PostCSS plugin that helps you use CSS modules. It allows you to scope CSS by automatically renaming classes and other selectors. It is similar to icss-utils in that it deals with CSS modules, but it is a full plugin rather than a set of utilities.

css-loader

css-loader is a loader for webpack that interprets `@import` and `url()` like `import/require()` and will resolve them. It also has features for handling CSS modules, which makes it similar to icss-utils. However, css-loader is more integrated with webpack's build system.

postcss-icss-selectors

This package is a PostCSS plugin that enables namespacing of CSS selectors according to the ICSS specification. It is similar to icss-utils in that it works with ICSS, but it focuses more on transforming selectors for scoping purposes.

README

ICSS Utils

replaceSymbols

Governs the way tokens are searched & replaced during the linking stage of ICSS loading.

This is broken into its own module in case the behaviour needs to be replicated in other PostCSS plugins (i.e. CSS Modules Values)

import { replaceSymbols, replaceValueSymbols } from "icss-utils";

replaceSymbols(css, replacements);
replaceValueSymbols(string, replacements);

Where:

• css is the PostCSS tree you're working with
• replacements is an JS object of symbol: "replacement" pairs, where all occurrences of symbol are replaced with replacement.

A symbol is a string of alphanumeric, - or _ characters. A replacement can be any string. They are replaced in the following places:

• In the value of a declaration, i.e. color: my_symbol; or box-shadow: 0 0 blur spread shadow-color
• In a media expression i.e. @media small {} or @media screen and not-large {}

extractICSS(css, removeRules = true, mode = 'auto')

Extracts and remove (if removeRules is equal true) from PostCSS tree :import, @icss-import, :export and @icss-export statements.

import postcss from "postcss";
import { extractICSS } from "icss-utils";

const css = postcss.parse(`
  :import(colors) {
    a: b;
  }
  :export {
    c: d;
  }
`);

extractICSS(css);
/*
  {
    icssImports: {
      colors: {
        a: 'b'
      }
    },
    icssExports: {
      c: 'd'
    }
  }
*/

By default both the pseudo and at-rule form of the import and export statements will be removed. Pass the mode option to limit to only one type.

createICSSRules(icssImports, icssExports, mode = 'rule')

Converts icss imports and exports definitions to postcss ast

createICSSRules(
  {
    colors: {
      a: "b",
    },
  },
  {
    c: "d",
  },
  // Need pass `rule` and `decl` from postcss
  // Please look at `Step 4` https://evilmartians.com/chronicles/postcss-8-plugin-migration
  postcss
);

By default it will create pseudo selector rules (:import and :export). Pass at-rule for mode to instead generate @icss-import and @icss-export, which may be more resilient to post processing by other tools.

License

ISC

---

Glen Maddern, Bogdan Chadkin and Evilebottnawi 2015-present.

Changelog

[5.1.0] - 2020-11-19

Features

• feat: support at-rule versions of import/export