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