postcss-color-mod-function

What is postcss-color-mod-function?

The postcss-color-mod-function package is a PostCSS plugin that allows you to modify colors using the color-mod() function in your CSS, following the CSS Color Module Level 4 specification. It enables you to apply color adjustments directly within your stylesheets, such as changing brightness, saturation, transparency, and more, without the need for pre-calculated color values.

What are postcss-color-mod-function's main functionalities?

Color Adjustments

Adjust the alpha transparency of a base color variable to 50%.

color: color-mod(var(--base-color) alpha(50%));

Color Blending

Blend the base color with black at a 30% mixture rate.

background-color: color-mod(var(--base-color) blend(black 30%));

Color Tinting and Shading

Apply a 20% tint and a 10% shade to the base color for the border.

border-color: color-mod(var(--base-color) tint(20%) shade(10%));

Other packages similar to postcss-color-mod-function

postcss-preset-env

postcss-preset-env is a PostCSS plugin that allows you to use future CSS features today. It includes the color-mod() function feature, among many others, and acts as a preset of various plugins including postcss-color-mod-function.

postcss-custom-properties

postcss-custom-properties is a plugin that allows you to use CSS custom properties (variables) in browsers that do not support them. While it doesn't offer color modification functions, it can be used in conjunction with other plugins to achieve similar results.

postcss-advanced-variables

postcss-advanced-variables extends CSS with variables, conditionals, and iterators. It doesn't directly offer color modification functions like postcss-color-mod-function, but it can be used to manipulate colors through custom logic.

README

PostCSS color-mod() Function

PostCSS color-mod() Function lets you modify colors using the color-mod() function in CSS, following the outdated version of CSS Color Module Level 4 specification (05 July 2016).

⚠️ color-mod() has been removed from Color Module Level 4 specification. (Here's why)

:root {
  --brand-red:      color-mod(yellow blend(red 50%));
  --brand-red-hsl:  color-mod(yellow blend(red 50% hsl));
  --brand-red-hwb:  color-mod(yellow blend(red 50% hwb));
  --brand-red-dark: color-mod(red blackness(20%));
}

/* becomes */

:root {
  --brand-red:      rgb(255, 127.5, 0);
  --brand-red-hsl:  rgb(255, 127.5, 255);
  --brand-red-hwb:  rgb(255, 127.5, 0);
  --brand-red-dark: rgb(204, 0, 0);
}

/* or, using stringifier(color) { return color.toString() } */

:root {
  --brand-red:      rgb(100% 50% 0% / 100%);
  --brand-red-hsl:  hsl(30 100% 50% / 100%);
  --brand-red-hwb:  hwb(30 0% 0% / 100%);
  --brand-red-dark: hwb(0 0% 20% / 100%);
}

Supported Colors

The color-mod() function accepts rgb(), legacy comma-separated rgb(), rgba(), hsl(), legacy comma-separated hsl(), hsla(), hwb(), and color-mod() colors, as well as 3, 4, 6, and 8 digit hex colors, and named colors without the need for additional plugins.

Implemention details are available in the specification.

Supported Color Adjusters

The color-mod() function accepts red(), green(), blue(), a() / alpha(), rgb(), h() / hue(), s() / saturation(), l() / lightness(), w() / whiteness(), b() / blackness(), tint(), shade(), blend(), blenda(), and contrast() color adjusters.

Implemention details are available in the specification.

Supported Variables

By default, var() variables will be used if their corresponding Custom Properties are found in a :root rule, or if a fallback value is specified.

Usage

Add PostCSS color-mod() Function to your project:

npm install postcss postcss-color-mod-function --save-dev

Use PostCSS color-mod() Function to process your CSS:

const postcssColorMod = require('postcss-color-mod-function');

postcssColorMod.process(YOUR_CSS /*, processOptions, pluginOptions */);

Or use it as a PostCSS plugin:

const postcss = require('postcss');
const postcssColorMod = require('postcss-color-mod-function');

postcss([
  postcssColorMod(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);

PostCSS color-mod() Function runs in all Node environments, with special instructions for:

Node	PostCSS CLI	Webpack	Create React App	Gulp	Grunt

Options

stringifier

The stringifier option defines how transformed colors will be produced in CSS. By default, legacy rgb() and rgba() colors are produced, but this can be easily updated to support [CSS Color Module Level 4 colors] colors.

import postcssColorMod from 'postcss-color-mod-function';

postcssColorMod({
  stringifier(color) {
    return color.toString(); // use CSS Color Module Level 4 colors (rgb, hsl, hwb)
  }
});

Future major releases of PostCSS color-mod() Function may reverse this functionality so that CSS Color Module Level 4 colors are produced by default.

unresolved

The unresolved option defines how unresolved functions and arguments should be handled. The available options are throw, warn, and ignore. The default option is to throw.

If ignore is used, the color-mod() function will remain unchanged.

import postcssColorMod from 'postcss-color-mod-function';

postcssColorMod({
  unresolved: 'ignore' // ignore unresolved color-mod() functions
});

transformVars

The transformVars option defines whether var() variables used within color-mod() should be transformed into their corresponding Custom Properties available in :root, or their fallback value if it is specified. By default, var() variables will be transformed.

However, because these transformations occur at build time, they cannot be considered accurate. Accurately resolving cascading variables relies on knowledge of the living DOM tree.

importFrom

The importFrom option allows you to import variables from other sources, which might be CSS, JS, and JSON files, and directly passed objects.

postcssColorMod({
  importFrom: 'path/to/file.css' // :root { --brand-dark: blue; --brand-main: var(--brand-dark); }
});

.brand-faded {
  color: color-mod(var(--brand-main) a(50%));
}

/* becomes */

.brand-faded {
  color: rgba(0, 0, 255, .5);
}

Multiple files can be passed into this option, and they will be parsed in the order they were received. JavaScript files, JSON files, and objects will need to namespace custom properties under a customProperties or custom-properties key.

postcssColorMod({
  importFrom: [
    'path/to/file.css',   // :root { --brand-dark: blue; --brand-main: var(--brand-dark); }
    'and/then/this.js',   // module.exports = { customProperties: { '--brand-dark': 'blue', '--brand-main': 'var(--brand-dark)' } }
    'and/then/that.json', // { "custom-properties": { "--brand-dark": "blue", "--brand-main": "var(--brand-dark)" } }
    {
      customProperties: {
        '--brand-dark': 'blue',
        '--brand-main': 'var(--brand-dark)'
      }
    }
  ]
});

Variables may reference other variables, and this plugin will attempt to resolve them. If transformVars is set to false then importFrom will not be used.

Changelog

4.1.0 (October 18, 2024)

• Drop postcss-values-parser in favor of postcss-value-parser