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# PostCSS Dir Pseudo Class [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS Logo" width="90" height="90" align="right">][postcss]
[![NPM Version][npm-img]][npm-url]
[![CSS Standard Status][css-img]][css-url]
[![Build Status][cli-img]][cli-url]
[<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord]
[PostCSS Dir Pseudo Class] lets you style by directionality using the `:dir()`
pseudo-class in CSS, following the [Selectors] specification.
[!['Can I use' table](https://caniuse.bitsofco.de/image/css-dir-pseudo.png)](https://caniuse.com/#feat=css-dir-pseudo)
```pcss
article h3:dir(rtl) {
margin-right: 10px;
}
article h3:dir(ltr) {
margin-left: 10px;
}
/* becomes */
[dir="rtl"] article h3 {
margin-right: 10px;
}
[dir="ltr"] article h3 {
margin-left: 10px;
}
```
### Maintaining Specificity
Using [PostCSS Dir Pseudo Class] will not impact selector weight, but it will
require having at least one `[dir]` attribute in your HTML. If you don’t have
_any_ `[dir]` attributes, consider using the following JavaScript:
```js
// force at least one dir attribute (this can run at any time)
document.documentElement.dir=document.documentElement.dir||'ltr';
```
If you absolutely cannot add a `[dir]` attribute in your HTML or even force one
via JavaScript, you can still work around this by presuming a direction in your
CSS using the [`dir` option](#dir-option), but understand that this will
sometimes increase selector weight by one element (`html`).
## Usage
Add [PostCSS Dir Pseudo Class] to your project:
```bash
npm install postcss-dir-pseudo-class --save-dev
```
Use [PostCSS Dir Pseudo Class] to process your CSS:
```js
const postcssDirPseudoClass = require('postcss-dir-pseudo-class');
postcssDirPseudoClass.process(YOUR_CSS /*, processOptions, pluginOptions */);
```
Or use it as a [PostCSS] plugin:
```js
const postcss = require('postcss');
const postcssDirPseudoClass = require('postcss-dir-pseudo-class');
postcss([
postcssDirPseudoClass(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);
```
[PostCSS Dir Pseudo Class] 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
### dir
The `dir` option allows you presume a direction in your CSS. By default, this
is not specified and you are required to include a direction `[dir]` attribute
somewhere in your HTML, preferably on the `html` element.
Here’s an example of using the `dir` option to presume a left-to-right
direction:
```js
postcssDirPseudoClass({ dir: 'ltr' });
```
```pcss
.example:dir(ltr) {
margin-left: 10px;
}
.example:dir(rtl) {
margin-right: 10px;
}
/* becomes */
html:not([dir="rtl"]) .example {
margin-left: 10px;
}
[dir="rtl"] .example {
margin-right: 10px;
}
```
### preserve
The `preserve` option determines whether the original `:dir()` rule should
remain in the CSS. By default, the original rule is not preserved.
```js
postcssDirPseudoClass({ preserve: true });
```
```pcss
article h3:dir(rtl) {
margin-right: 10px;
}
article h3:dir(ltr) {
margin-left: 10px;
}
/* becomes */
[dir="rtl"] article h3 {
margin-right: 10px;
}
article h3:dir(rtl) {
margin-right: 10px;
}
[dir="ltr"] article h3 {
margin-left: 10px;
}
article h3:dir(ltr) {
margin-left: 10px;
}
```
[cli-img]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml/badge.svg
[cli-url]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml?query=workflow/test
[css-img]: https://cssdb.org/images/badges/dir-pseudo-class.svg
[css-url]: https://cssdb.org/#dir-pseudo-class
[discord]: https://discord.gg/bUadyRwkJS
[npm-img]: https://img.shields.io/npm/v/postcss-dir-pseudo-class.svg
[npm-url]: https://www.npmjs.com/package/postcss-dir-pseudo-class
[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 Dir Pseudo Class]: https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-dir-pseudo-class
[Selectors]: https://www.w3.org/TR/selectors-4/#the-dir-pseudo