postcss-dir-pseudo-class

What is postcss-dir-pseudo-class?

The postcss-dir-pseudo-class package is a PostCSS plugin that allows you to use the :dir pseudo-class in CSS, enabling styling based on the directionality of text (e.g., left-to-right or right-to-left). This is particularly useful for creating styles that need to adapt to different language directionality, such as supporting both English (LTR) and Arabic or Hebrew (RTL) without having to write separate CSS rules for each.

What are postcss-dir-pseudo-class's main functionalities?

Directional Styling

Allows styling elements differently based on the text direction. This is useful for creating layouts and designs that adapt to both LTR and RTL languages.

/* Input CSS */
:dir(ltr) .selector { float: left; }
:dir(rtl) .selector { float: right; }

/* Output CSS */
.selector:dir(ltr) { float: left; }
.selector:dir(rtl) { float: right; }

Fallback Support

Generates fallbacks for browsers that do not support the :dir pseudo-class, using the [dir] attribute selector instead. This ensures compatibility across a wider range of browsers.

/* Input CSS */
:dir(ltr) .selector { float: left; }
:dir(rtl) .selector { float: right; }

/* Output CSS with fallback */
[dir='ltr'] .selector { float: left; }
[dir='rtl'] .selector { float: right; }

Other packages similar to postcss-dir-pseudo-class

rtlcss

RTLCSS is a framework for converting Left-To-Right (LTR) CSS to Right-To-Left (RTL). While postcss-dir-pseudo-class focuses on providing directional styling capabilities within CSS, RTLCSS specifically targets the conversion of existing LTR CSS to RTL, making it more suitable for projects that need to automate the generation of RTL stylesheets from their LTR counterparts.

postcss-rtl

Similar to RTLCSS, postcss-rtl is a PostCSS plugin designed to convert LTR CSS to RTL. It offers a different approach and syntax for defining directional styles compared to postcss-dir-pseudo-class, focusing more on the conversion aspect rather than enabling the direct use of :dir pseudo-class in stylesheets.

README

PostCSS Dir Pseudo Class

npm install postcss-dir-pseudo-class --save-dev

PostCSS Dir Pseudo Class lets you style by directionality using the :dir() pseudo-class in CSS, following the Selectors specification.

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:

// 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, but understand that this will sometimes increase selector weight by one element (html).

Usage

Add PostCSS Dir Pseudo Class to your project:

npm install postcss postcss-dir-pseudo-class --save-dev

Use it as a PostCSS plugin:

const postcss = require('postcss');
const postcssDirPseudoClass = require('postcss-dir-pseudo-class');

postcss([
	postcssDirPseudoClass(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);

Options

preserve

The preserve option determines whether the original notation is preserved. By default, it is not preserved.

postcssDirPseudoClass({ preserve: true })

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;
}

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.

postcssDirPseudoClass({ dir: 'ltr' });

article h3:dir(rtl) {
	margin-right: 10px;
}

article h3:dir(ltr) {
	margin-left: 10px;
}

/* becomes */

[dir="rtl"] article h3 {
	margin-right: 10px;
}

html:not([dir="rtl"]) article h3 {
	margin-left: 10px;
}

postcssDirPseudoClass({ dir: 'rtl' });

article h3:dir(rtl) {
	margin-right: 10px;
}

article h3:dir(ltr) {
	margin-left: 10px;
}

/* becomes */

html:not([dir="ltr"]) article h3 {
	margin-right: 10px;
}

[dir="ltr"] article h3 {
	margin-left: 10px;
}

shadow

The shadow option determines whether the CSS is assumed to be used in Shadow DOM with Custom Elements.

postcssDirPseudoClass({ shadow: true })

article h3:dir(rtl) {
	margin-right: 10px;
}

article h3:dir(ltr) {
	margin-left: 10px;
}

/* becomes */

:host-context([dir="rtl"]) article h3 {
	margin-right: 10px;
}

:host-context([dir="ltr"]) article h3 {
	margin-left: 10px;
}