# PostCSS Focus Within [
][postcss]
[
][npm-url]
[
][css-url]
[
][cli-url]
[
][discord]
[PostCSS Focus Within] lets you use the `:focus-within` pseudo-class in CSS,
following the [Selectors Level 4 specification].
It is the companion to the [focus-within polyfill].
[](https://caniuse.com/#feat=css-focus-within)
```css
.my-form-field:focus-within label {
background-color: yellow;
}
/* becomes */
.my-form-field[focus-within] label {
background-color: yellow;
}
.my-form-field:focus-within label {
background-color: yellow;
}
```
[PostCSS Focus Within] duplicates rules using the `:focus-within` pseudo-class
with a `[focus-within]` attribute selector, the same selector used by the
[focus-within polyfill]. This replacement selector can be changed using the
`replaceWith` option. Also, the preservation of the original `:focus-within`
rule can be disabled using the `preserve` option.
## Usage
Add [PostCSS Focus Within] to your project:
```bash
npm install postcss postcss-focus-within --save-dev
```
Use [PostCSS Focus Within] to process your CSS:
```js
const postcssFocusWithin = require('postcss-focus-within');
postcssFocusWithin.process(YOUR_CSS /*, processOptions, pluginOptions */);
```
Or use it as a [PostCSS] plugin:
```js
const postcss = require('postcss');
const postcssFocusWithin = require('postcss-focus-within');
postcss([
postcssFocusWithin(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);
```
[PostCSS Focus Within] 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 defines whether the original selector should remain. By
default, the original selector is preserved.
```js
focusWithin({ preserve: false });
```
```css
.my-form-field:focus-within label {
background-color: yellow;
}
/* becomes */
.my-form-field[focus-within] label {
background-color: yellow;
}
```
### replaceWith
The `replaceWith` option defines the selector to replace `:focus-within`. By
default, the replacement selector is `[focus-within]`.
```js
focusWithin({ replaceWith: '.focus-within' });
```
```css
.my-form-field:focus-within label {
background-color: yellow;
}
/* becomes */
.my-form-field.focus-within label {
background-color: yellow;
}
.my-form-field:focus-within label {
background-color: yellow;
}
```
[css-url]: https://cssdb.org/#focus-within-pseudo-class
[cli-url]: https://github.com/csstools/postcss-plugins/tree/main/postcss-focus-within/actions/workflows/test.yml?query=workflow/test
[discord]: https://discord.gg/bUadyRwkJS
[npm-url]: https://www.npmjs.com/package/postcss-focus-within
[focus-within polyfill]: https://github.com/jsxtools/focus-within
[Gulp PostCSS]: https://github.com/postcss/gulp-postcss
[Grunt PostCSS]: https://github.com/nDmitry/grunt-postcss
[PostCSS]: https://github.com/postcss/postcss
[PostCSS Focus Within]: https://github.com/csstools/postcss-plugins/tree/main/postcss-focus-within
[PostCSS Loader]: https://github.com/postcss/postcss-loader
[Selectors Level 4 specification]: https://www.w3.org/TR/selectors-4/#the-focus-within-pseudo