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207 lines
5.7 KiB
207 lines
5.7 KiB
# PostCSS Custom Properties [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS" width="90" height="90" align="right">][postcss] |
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[![NPM Version][npm-img]][npm-url] |
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[![CSS Standard Status][css-img]][css-url] |
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[![Build Status][cli-img]][cli-url] |
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[<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord] |
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[PostCSS Custom Properties] lets you use Custom Properties in CSS, following |
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the [CSS Custom Properties] specification. |
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[!['Can I use' table](https://caniuse.bitsofco.de/image/css-variables.png)](https://caniuse.com/#feat=css-variables) |
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```pcss |
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:root { |
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--color: red; |
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} |
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h1 { |
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color: var(--color); |
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} |
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/* becomes */ |
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:root { |
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--color: red; |
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} |
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h1 { |
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color: red; |
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color: var(--color); |
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} |
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``` |
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**Note:** This plugin only processes variables that are defined in the `:root` selector. |
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## Usage |
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Add [PostCSS Custom Properties] to your project: |
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```bash |
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npm install postcss-custom-properties --save-dev |
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``` |
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Use [PostCSS Custom Properties] as a [PostCSS] plugin: |
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```js |
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const postcss = require('postcss'); |
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const postcssCustomProperties = require('postcss-custom-properties'); |
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postcss([ |
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postcssCustomProperties(/* pluginOptions */) |
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]).process(YOUR_CSS /*, processOptions */); |
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``` |
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[PostCSS Custom Properties] runs in all Node environments, with special instructions for: |
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| [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) | |
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| --- | --- | --- | --- | --- | --- | |
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## Options |
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### preserve |
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The `preserve` option determines whether Custom Properties and properties using |
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custom properties should be preserved in their original form. By default, both |
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of these are preserved. |
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```js |
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postcssCustomProperties({ |
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preserve: false |
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}); |
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``` |
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```pcss |
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:root { |
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--color: red; |
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} |
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h1 { |
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color: var(--color); |
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} |
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/* becomes */ |
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h1 { |
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color: red; |
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} |
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``` |
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### importFrom |
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The `importFrom` option specifies sources where Custom Properties can be imported |
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from, which might be CSS, JS, and JSON files, functions, and directly passed |
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objects. |
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```js |
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postcssCustomProperties({ |
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importFrom: 'path/to/file.css' // => :root { --color: red } |
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}); |
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``` |
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```pcss |
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h1 { |
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color: var(--color); |
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} |
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/* becomes */ |
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h1 { |
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color: red; |
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} |
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``` |
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Multiple sources can be passed into this option, and they will be parsed in the |
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order they are received. JavaScript files, JSON files, functions, and objects |
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will need to namespace Custom Properties using the `customProperties` or |
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`custom-properties` key. |
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```js |
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postcssCustomProperties({ |
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importFrom: [ |
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'path/to/file.css', // :root { --color: red; } |
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'and/then/this.js', // module.exports = { customProperties: { '--color': 'red' } } |
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'and/then/that.json', // { "custom-properties": { "--color": "red" } } |
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{ |
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customProperties: { '--color': 'red' } |
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}, |
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() => { |
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const customProperties = { '--color': 'red' }; |
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return { customProperties }; |
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} |
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] |
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}); |
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``` |
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See example imports written in [CSS](test/import-properties.css), |
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[JS](test/import-properties.js), and [JSON](test/import-properties.json). |
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### overrideImportFromWithRoot |
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The `overrideImportFromWithRoot` option determines if properties added via `importFrom` are overridden by properties that exist in `:root`. |
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Defaults to `false`. |
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```js |
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postcssCustomProperties({ |
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overrideImportFromWithRoot: true |
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}); |
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``` |
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### exportTo |
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The `exportTo` option specifies destinations where Custom Properties can be exported |
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to, which might be CSS, JS, and JSON files, functions, and directly passed |
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objects. |
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```js |
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postcssCustomProperties({ |
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exportTo: 'path/to/file.css' // :root { --color: red; } |
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}); |
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``` |
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Multiple destinations can be passed into this option, and they will be parsed |
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in the order they are received. JavaScript files, JSON files, and objects will |
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need to namespace Custom Properties using the `customProperties` or |
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`custom-properties` key. |
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```js |
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const cachedObject = { customProperties: {} }; |
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postcssCustomProperties({ |
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exportTo: [ |
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'path/to/file.css', // :root { --color: red; } |
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'and/then/this.js', // module.exports = { customProperties: { '--color': 'red' } } |
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'and/then/this.mjs', // export const customProperties = { '--color': 'red' } } |
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'and/then/that.json', // { "custom-properties": { "--color": "red" } } |
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'and/then/that.scss', // $color: red; |
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cachedObject, |
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customProperties => { |
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customProperties // { '--color': 'red' } |
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} |
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] |
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}); |
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``` |
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See example exports written to [CSS](test/export-properties.css), |
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[JS](test/export-properties.js), [MJS](test/export-properties.mjs), |
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[JSON](test/export-properties.json) and [SCSS](test/export-properties.scss). |
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### disableDeprecationNotice |
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Silence the deprecation notice that is printed to the console when using `importFrom` or `exportTo`. |
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> "importFrom" and "exportTo" will be removed in a future version of postcss-custom-properties. |
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> Check the discussion on github for more details. https://github.com/csstools/postcss-plugins/discussions/192 |
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[cli-img]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml/badge.svg |
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[cli-url]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml?query=workflow/test |
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[css-img]: https://cssdb.org/images/badges/custom-properties.svg |
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[css-url]: https://cssdb.org/#custom-properties |
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[discord]: https://discord.gg/bUadyRwkJS |
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[npm-img]: https://img.shields.io/npm/v/postcss-custom-properties.svg |
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[npm-url]: https://www.npmjs.com/package/postcss-custom-properties |
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[CSS Custom Properties]: https://www.w3.org/TR/css-variables-1/ |
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[PostCSS]: https://github.com/postcss/postcss |
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[PostCSS Custom Properties]: https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-custom-properties
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