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https://github.com/postcss/postcss-custom-properties
Use Custom Properties in CSS
https://github.com/postcss/postcss-custom-properties
Last synced: about 1 month ago
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Use Custom Properties in CSS
- Host: GitHub
- URL: https://github.com/postcss/postcss-custom-properties
- Owner: postcss
- License: mit
- Archived: true
- Created: 2014-07-29T05:48:21.000Z (over 10 years ago)
- Default Branch: main
- Last Pushed: 2022-02-18T13:02:35.000Z (over 2 years ago)
- Last Synced: 2024-04-14T02:32:51.102Z (7 months ago)
- Language: JavaScript
- Homepage: https://postcss.github.io/postcss-custom-properties
- Size: 539 KB
- Stars: 596
- Watchers: 11
- Forks: 81
- Open Issues: 43
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE.md
Awesome Lists containing this project
- stars - postcss/postcss-custom-properties
- awesome - postcss-custom-properties - Use Custom Properties in CSS (JavaScript)
- awesome-list - postcss-custom-properties
README
# PostCSS Custom Properties [
][postcss]
[![NPM Version][npm-img]][npm-url]
[![CSS Standard Status][css-img]][css-url]
[![Build Status][cli-img]][cli-url]
[![Support Chat][git-img]][git-url]
[PostCSS Custom Properties] lets you use Custom Properties in CSS, following
the [CSS Custom Properties] specification.
[](https://caniuse.com/#feat=css-variables)
```pcss
:root {
--color: red;
}
h1 {
color: var(--color);
}
/* becomes */
:root {
--color: red;
}
h1 {
color: red;
color: var(--color);
}
```
**Note:** This plugin only processes variables that are defined in the `:root` selector.
## Usage
Add [PostCSS Custom Properties] to your project:
```bash
npm install postcss-custom-properties --save-dev
```
Use [PostCSS Custom Properties] to process your CSS:
```js
const postcssCustomProperties = require('postcss-custom-properties');
postcssCustomProperties.process(YOUR_CSS /*, processOptions, pluginOptions */);
```
Or use it as a [PostCSS] plugin:
```js
const postcss = require('postcss');
const postcssCustomProperties = require('postcss-custom-properties');
postcss([
postcssCustomProperties(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);
```
[PostCSS Custom Properties] runs in all Node environments, with special instructions for:
| [Node](INSTALL.md#node) | [PostCSS CLI](INSTALL.md#postcss-cli) | [Webpack](INSTALL.md#webpack) | [Create React App](INSTALL.md#create-react-app) | [Gulp](INSTALL.md#gulp) | [Grunt](INSTALL.md#grunt) |
| --- | --- | --- | --- | --- | --- |
## Options
### preserve
The `preserve` option determines whether Custom Properties and properties using
custom properties should be preserved in their original form. By default, both
of these are preserved.
```js
postcssCustomProperties({
preserve: false
});
```
```pcss
:root {
--color: red;
}
h1 {
color: var(--color);
}
/* becomes */
h1 {
color: red;
}
```
### importFrom
The `importFrom` option specifies sources where Custom Properties can be imported
from, which might be CSS, JS, and JSON files, functions, and directly passed
objects.
```js
postcssCustomProperties({
importFrom: 'path/to/file.css' // => :root { --color: red }
});
```
```pcss
h1 {
color: var(--color);
}
/* becomes */
h1 {
color: red;
}
```
Multiple sources can be passed into this option, and they will be parsed in the
order they are received. JavaScript files, JSON files, functions, and objects
will need to namespace Custom Properties using the `customProperties` or
`custom-properties` key.
```js
postcssCustomProperties({
importFrom: [
'path/to/file.css', // :root { --color: red; }
'and/then/this.js', // module.exports = { customProperties: { '--color': 'red' } }
'and/then/that.json', // { "custom-properties": { "--color": "red" } }
{
customProperties: { '--color': 'red' }
},
() => {
const customProperties = { '--color': 'red' };
return { customProperties };
}
]
});
```
See example imports written in [CSS](test/import-properties.css),
[JS](test/import-properties.js), and [JSON](test/import-properties.json).
### exportTo
The `exportTo` option specifies destinations where Custom Properties can be exported
to, which might be CSS, JS, and JSON files, functions, and directly passed
objects.
```js
postcssCustomProperties({
exportTo: 'path/to/file.css' // :root { --color: red; }
});
```
Multiple destinations can be passed into this option, and they will be parsed
in the order they are received. JavaScript files, JSON files, and objects will
need to namespace Custom Properties using the `customProperties` or
`custom-properties` key.
```js
const cachedObject = { customProperties: {} };
postcssCustomProperties({
exportTo: [
'path/to/file.css', // :root { --color: red; }
'and/then/this.js', // module.exports = { customProperties: { '--color': 'red' } }
'and/then/this.mjs', // export const customProperties = { '--color': 'red' } }
'and/then/that.json', // { "custom-properties": { "--color": "red" } }
'and/then/that.scss', // $color: red;
cachedObject,
customProperties => {
customProperties // { '--color': 'red' }
}
]
});
```
See example exports written to [CSS](test/export-properties.css),
[JS](test/export-properties.js), [MJS](test/export-properties.mjs),
[JSON](test/export-properties.json) and [SCSS](test/export-properties.scss).
[cli-img]: https://img.shields.io/travis/postcss/postcss-custom-properties/master.svg
[cli-url]: https://travis-ci.org/postcss/postcss-custom-properties
[css-img]: https://github.com/postcss/postcss-custom-properties/workflows/test/badge.svg
[css-url]: https://github.com/postcss/postcss-custom-properties/actions/workflows/test.yml?query=workflow/test
[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-custom-properties.svg
[npm-url]: https://www.npmjs.com/package/postcss-custom-properties
[CSS Custom Properties]: https://www.w3.org/TR/css-variables-1/
[PostCSS]: https://github.com/postcss/postcss
[PostCSS Custom Properties]: https://github.com/postcss/postcss-custom-properties