168 lines
4.3 KiB
Markdown
168 lines
4.3 KiB
Markdown
# PostCSS Dir Pseudo Class [<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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[![Support Chat][git-img]][git-url]
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[PostCSS Dir Pseudo Class] lets you style by directionality using the `:dir()`
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pseudo-class in CSS, following the [Selectors] specification.
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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[dir="rtl"] article h3 {
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margin-right: 10px;
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}
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[dir="ltr"] article h3 {
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margin-left: 10px;
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}
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```
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### Maintaining Specificity
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Using [PostCSS Dir Pseudo Class] will not impact selector weight, but it will
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require having at least one `[dir]` attribute in your HTML. If you don’t have
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_any_ `[dir]` attributes, consider using the following JavaScript:
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```js
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// force at least one dir attribute (this can run at any time)
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document.documentElement.dir=document.documentElement.dir||'ltr';
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```
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If you absolutely cannot add a `[dir]` attribute in your HTML or even force one
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via JavaScript, you can still work around this by presuming a direction in your
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CSS using the [`dir` option](#dir-option), but understand that this will
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sometimes increase selector weight by one element (`html`).
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## Usage
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Add [PostCSS Dir Pseudo Class] to your project:
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```bash
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npm install postcss-dir-pseudo-class --save-dev
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```
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Use [PostCSS Dir Pseudo Class] to process your CSS:
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```js
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const postcssDirPseudoClass = require('postcss-dir-pseudo-class');
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postcssDirPseudoClass.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 postcssDirPseudoClass = require('postcss-dir-pseudo-class');
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postcss([
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postcssDirPseudoClass(/* pluginOptions */)
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]).process(YOUR_CSS /*, processOptions */);
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```
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[PostCSS Dir Pseudo Class] runs in all Node environments, with special 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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### dir
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The `dir` option allows you presume a direction in your CSS. By default, this
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is not specified and you are required to include a direction `[dir]` attribute
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somewhere in your HTML, preferably on the `html` element.
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Here’s an example of using the `dir` option to presume a left-to-right
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direction:
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```js
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postcssDirPseudoClass({ dir: 'ltr' });
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```
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```pcss
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.example:dir(ltr) {
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margin-left: 10px;
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}
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.example:dir(rtl) {
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margin-right: 10px;
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}
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/* becomes */
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html:not([dir="rtl"]) .example {
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margin-left: 10px;
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}
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[dir="rtl"] .example {
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margin-right: 10px;
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}
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```
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### preserve
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The `preserve` option determines whether the original `:dir()` rule should
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remain in the CSS. By default, the original rule is not preserved.
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```js
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postcssDirPseudoClass({ preserve: true });
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```
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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[dir="rtl"] article h3 {
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margin-right: 10px;
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}
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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[dir="ltr"] article h3 {
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margin-left: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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```
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[cli-img]: https://img.shields.io/travis/jonathantneal/postcss-dir-pseudo-class.svg
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[cli-url]: https://travis-ci.org/jonathantneal/postcss-dir-pseudo-class
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[css-img]: https://cssdb.org/badge/dir-pseudo-class.svg
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[css-url]: https://cssdb.org/#dir-pseudo-class
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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-dir-pseudo-class.svg
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[npm-url]: https://www.npmjs.com/package/postcss-dir-pseudo-class
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[win-img]: https://img.shields.io/appveyor/ci/jonathantneal/postcss-dir-pseudo-class.svg
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[win-url]: https://ci.appveyor.com/project/jonathantneal/postcss-dir-pseudo-class
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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 Dir Pseudo Class]: https://github.com/jonathantneal/postcss-dir-pseudo-class
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[Selectors]: https://www.w3.org/TR/selectors-4/#the-dir-pseudo
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