PostCSS color-mod() Function [][postcss]

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[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function in CSS, following the outdated version of [CSS Color Module Level 4] specification (05 July 2016).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)

``pcss
: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%);
}
`

$3

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.

$3

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.

$3

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:

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

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

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

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

Or use it as a [PostCSS] plugin:

`js
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

$3

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.

`js
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.

$3

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.

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

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

$3

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.

$3

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

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

`pcss
.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.

`js
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.

[cli-img]: https://img.shields.io/travis/jonathantneal/postcss-color-mod-function.svg
[cli-url]: https://travis-ci.org/jonathantneal/postcss-color-mod-function
[css-img]: https://cssdb.org/badge/color-mod-function.svg
[css-url]: https://preset-env.cssdb.org/features#color-mod-function
[git-img]: https://img.shields.io/badge/support-chat-blue.svg
[git-url]: https://gitter.im/postcss/postcss
[npm-img]: https://img.shields.io/npm/v/postcss-color-mod-function.svg
[npm-url]: https://www.npmjs.com/package/postcss-color-mod-function

[CSS Color Module Level 4]: https://www.w3.org/TR/2016/WD-css-color-4-20160705/#funcdef-color-mod
[Gulp PostCSS]: https://github.com/postcss/gulp-postcss
[Grunt PostCSS]: https://github.com/nDmitry/grunt-postcss
[PostCSS]: https://github.com/postcss/postcss
[PostCSS color-mod() Function]: https://github.com/jonathantneal/postcss-color-mod-function