167 lines
4.7 KiB
Markdown
167 lines
4.7 KiB
Markdown
# PostCSS Custom Selectors [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS Logo" width="90" height="90" align="right">][postcss]
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[<img alt="npm version" src="https://img.shields.io/npm/v/postcss-custom-selectors.svg" height="20">][npm-url] [<img alt="CSS Standard Status" src="https://cssdb.org/images/badges/custom-selectors.svg" height="20">][css-url] [<img alt="Build Status" src="https://github.com/csstools/postcss-plugins/workflows/test/badge.svg" height="20">][cli-url] [<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord]
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[PostCSS Custom Selectors] lets you define `@custom-selector` in CSS following the [Custom Selectors Specification].
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```pcss
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@custom-selector :--heading h1, h2, h3;
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article :--heading + p {
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margin-top: 0;
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}
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/* becomes */
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article h1 + p,article h2 + p,article h3 + p {
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margin-top: 0;
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}
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```
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## Usage
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Add [PostCSS Custom Selectors] to your project:
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```bash
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npm install postcss postcss-custom-selectors --save-dev
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```
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Use it as a [PostCSS] plugin:
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```js
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const postcss = require('postcss');
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const postcssCustomSelectors = require('postcss-custom-selectors');
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postcss([
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postcssCustomSelectors(/* pluginOptions */)
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]).process(YOUR_CSS /*, processOptions */);
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```
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[PostCSS Custom Selectors] runs in all Node environments, with special
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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 the original notation
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is preserved. By default, it is not preserved.
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```js
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postcssCustomSelectors({ preserve: true })
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```
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```pcss
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@custom-selector :--heading h1, h2, h3;
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article :--heading + p {
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margin-top: 0;
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}
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/* becomes */
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@custom-selector :--heading h1, h2, h3;
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article h1 + p,article h2 + p,article h3 + p {
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margin-top: 0;
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}
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article :--heading + p {
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margin-top: 0;
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}
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```
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### importFrom
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The `importFrom` option specifies sources where custom selectors can be
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imported from, which might be CSS, JS, and JSON files, functions, and directly
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passed objects.
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```js
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postcssCustomSelectors({
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importFrom: 'path/to/file.css' // => @custom-selector :--heading h1, h2, h3;
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});
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```
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```pcss
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article :--heading + p {
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margin-top: 0;
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}
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/* becomes */
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article h1 + p, article h2 + p, article h3 + p {}
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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 selectors using the `customProperties` or
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`custom-properties` key.
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```js
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postcssCustomSelectors({
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importFrom: [
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'path/to/file.css',
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'and/then/this.js',
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'and/then/that.json',
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{
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customSelectors: { ':--heading': 'h1, h2, h3' }
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},
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() => {
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const customProperties = { ':--heading': 'h1, h2, h3' };
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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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### exportTo
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The `exportTo` option specifies destinations where custom selectors can be
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exported to, which might be CSS, JS, and JSON files, functions, and directly
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passed objects.
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```js
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postcssCustomSelectors({
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exportTo: 'path/to/file.css' // @custom-selector :--heading h1, h2, h3;
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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 selectors using the `customProperties` or
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`custom-properties` key.
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```js
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const cachedObject = { customSelectors: {} };
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postcssCustomSelectors({
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exportTo: [
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'path/to/file.css', // @custom-selector :--heading h1, h2, h3;
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'and/then/this.js', // module.exports = { customSelectors: { ':--heading': 'h1, h2, h3' } }
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'and/then/this.mjs', // export const customSelectors = { ':--heading': 'h1, h2, h3' } }
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'and/then/that.json', // { "custom-selectors": { ":--heading": "h1, h2, h3" } }
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cachedObject,
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customProperties => {
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customProperties // { ':--heading': 'h1, h2, h3' }
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}
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]
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});
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```
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[cli-url]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml?query=workflow/test
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[css-url]: https://cssdb.org/#custom-selectors
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[discord]: https://discord.gg/bUadyRwkJS
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[npm-url]: https://www.npmjs.com/package/postcss-custom-selectors
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[Gulp PostCSS]: https://github.com/postcss/gulp-postcss
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[Grunt PostCSS]: https://github.com/nDmitry/grunt-postcss
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[PostCSS]: https://github.com/postcss/postcss
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[PostCSS Loader]: https://github.com/postcss/postcss-loader
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[PostCSS Custom Selectors]: https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-custom-selectors
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[Custom Selectors Specification]: https://drafts.csswg.org/css-extensions/#custom-selectors
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