132 lines
3.6 KiB
Markdown
132 lines
3.6 KiB
Markdown
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# PostCSS Focus Within [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS Logo" 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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[![Gitter Chat][git-img]][git-url]
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[PostCSS Focus Within] lets you use the `:focus-within` pseudo-class in CSS,
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following the [Selectors Level 4 specification].
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It is the companion to the [focus-within polyfill].
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```css
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.my-form-field:focus-within label {
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background-color: yellow;
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}
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/* becomes */
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.my-form-field[focus-within] label {
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background-color: yellow;
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}
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.my-form-field:focus-within label {
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background-color: yellow;
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}
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```
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[PostCSS Focus Within] duplicates rules using the `:focus-within` pseudo-class
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with a `[focus-within]` attribute selector, the same selector used by the
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[focus-within polyfill]. This replacement selector can be changed using the
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`replaceWith` option. Also, the preservation of the original `:focus-within`
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rule can be disabled using the `preserve` option.
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## Usage
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Add [PostCSS Focus Within] to your project:
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```bash
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npm install postcss-focus-within --save-dev
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```
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Use [PostCSS Focus Within] to process your CSS:
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```js
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const postcssFocusWithin = require('postcss-focus-within');
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postcssFocusWithin.process(YOUR_CSS /*, processOptions, pluginOptions */);
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```
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Or use it as a [PostCSS] plugin:
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```js
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const postcss = require('postcss');
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const postcssFocusWithin = require('postcss-focus-within');
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postcss([
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postcssFocusWithin(/* pluginOptions */)
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]).process(YOUR_CSS /*, processOptions */);
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```
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[PostCSS Focus Within] 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 defines whether the original selector should remain. By
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default, the original selector is preserved.
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```js
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focusWithin({ preserve: false });
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```
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```css
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.my-form-field:focus-within label {
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background-color: yellow;
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}
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/* becomes */
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.my-form-field[focus-within] label {
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background-color: yellow;
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}
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```
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### replaceWith
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The `replaceWith` option defines the selector to replace `:focus-within`. By
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default, the replacement selector is `[focus-within]`.
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```js
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focusWithin({ replaceWith: '.focus-within' });
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```
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```css
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.my-form-field:focus-within label {
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background-color: yellow;
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}
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/* becomes */
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.my-form-field.focus-within label {
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background-color: yellow;
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}
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.my-form-field:focus-within label {
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background-color: yellow;
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}
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```
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[css-img]: https://cssdb.org/badge/focus-within-pseudo-class.svg
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[css-url]: https://cssdb.org/#focus-within-pseudo-class
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[cli-img]: https://img.shields.io/travis/jonathantneal/postcss-focus-within.svg
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[cli-url]: https://travis-ci.org/jonathantneal/postcss-focus-within
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[git-img]: https://img.shields.io/badge/support-chat-blue.svg
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[git-url]: https://gitter.im/postcss/postcss
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[npm-img]: https://img.shields.io/npm/v/postcss-focus-within.svg
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[npm-url]: https://www.npmjs.com/package/postcss-focus-within
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[focus-within polyfill]: https://github.com/jonathantneal/focus-within
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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 Focus Within]: https://github.com/jonathantneal/postcss-focus-within
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[PostCSS Loader]: https://github.com/postcss/postcss-loader
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[Selectors Level 4 specification]: https://www.w3.org/TR/selectors-4/#the-focus-within-pseudo
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