196 lines
4.0 KiB
Markdown
196 lines
4.0 KiB
Markdown
# PostCSS Nesting [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS" width="90" height="90" align="right">][postcss]
|
|
|
|
[![NPM Version][npm-img]][npm-url]
|
|
[![CSS Standard Status][css-img]][css-url]
|
|
[<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord]
|
|
|
|
[PostCSS Nesting] lets you nest style rules inside each other, following the
|
|
[CSS Nesting] specification. If you want nested rules the same way [Sass] works
|
|
you might want to use [PostCSS Nested] instead.
|
|
|
|
```pcss
|
|
a, b {
|
|
color: red;
|
|
|
|
/* "&" comes first */
|
|
& c, & d {
|
|
color: white;
|
|
}
|
|
|
|
/* "&" comes later, requiring "@nest" */
|
|
@nest e & {
|
|
color: yellow;
|
|
}
|
|
}
|
|
|
|
/* becomes */
|
|
|
|
a, b {
|
|
color: red;
|
|
}
|
|
|
|
a c, a d, b c, b d {
|
|
color: white;
|
|
}
|
|
|
|
e a, e b {
|
|
color: yellow;
|
|
}
|
|
```
|
|
|
|
## Usage
|
|
|
|
Add [PostCSS Nesting] to your project:
|
|
|
|
```bash
|
|
npm install postcss-nesting --save-dev
|
|
```
|
|
|
|
Use [PostCSS Nesting] as a [PostCSS] plugin:
|
|
|
|
```js
|
|
import postcss from 'postcss';
|
|
import postcssNesting from 'postcss-nesting';
|
|
|
|
postcss([
|
|
postcssNesting(/* pluginOptions */)
|
|
]).process(YOUR_CSS /*, processOptions */);
|
|
```
|
|
|
|
[PostCSS Nesting] runs in all Node environments, with special instructions for:
|
|
|
|
| [Node](INSTALL.md#node) | [Webpack](INSTALL.md#webpack) | [Create React App](INSTALL.md#create-react-app) | [Gulp](INSTALL.md#gulp) | [Grunt](INSTALL.md#grunt) |
|
|
| --- | --- | --- | --- | --- |
|
|
|
|
### Deno
|
|
|
|
You can also use [PostCSS Nesting] on [Deno]:
|
|
|
|
```js
|
|
import postcss from "https://deno.land/x/postcss/mod.js";
|
|
import postcssNesting from "https://cdn.jsdelivr.net/npm/postcss-nesting@10/mod.js";
|
|
|
|
await postcss([postcssNesting]).process(YOUR_CSS /*, processOptions */);
|
|
```
|
|
|
|
## Options
|
|
|
|
### noIsPseudoSelector
|
|
|
|
#### Specificity
|
|
|
|
Before :
|
|
|
|
```css
|
|
#alpha,
|
|
.beta {
|
|
&:hover {
|
|
order: 1;
|
|
}
|
|
}
|
|
```
|
|
|
|
After **without** the option :
|
|
|
|
```js
|
|
postcssNesting()
|
|
```
|
|
|
|
```css
|
|
:is(#alpha,.beta):hover {
|
|
order: 1;
|
|
}
|
|
```
|
|
|
|
_`.beta:hover` has specificity as if `.beta` where an id selector, matching the specification._
|
|
|
|
[specificity: 1, 1, 0](https://polypane.app/css-specificity-calculator/#selector=%3Ais(%23alpha%2C.beta)%3Ahover)
|
|
|
|
After **with** the option :
|
|
|
|
```js
|
|
postcssNesting({
|
|
noIsPseudoSelector: true
|
|
})
|
|
```
|
|
|
|
```css
|
|
#alpha:hover, .beta:hover {
|
|
order: 1;
|
|
}
|
|
```
|
|
|
|
_`.beta:hover` has specificity as if `.beta` where a class selector, conflicting with the specification._
|
|
|
|
[specificity: 0, 2, 0](https://polypane.app/css-specificity-calculator/#selector=.beta%3Ahover)
|
|
|
|
|
|
#### Complex selectors
|
|
|
|
Before :
|
|
|
|
```css
|
|
.alpha > .beta {
|
|
& + & {
|
|
order: 2;
|
|
}
|
|
}
|
|
```
|
|
|
|
After **without** the option :
|
|
|
|
```js
|
|
postcssNesting()
|
|
```
|
|
|
|
```css
|
|
:is(.alpha > .beta) + :is(.alpha > .beta) {
|
|
order: 2;
|
|
}
|
|
```
|
|
|
|
After **with** the option :
|
|
|
|
```js
|
|
postcssNesting({
|
|
noIsPseudoSelector: true
|
|
})
|
|
```
|
|
|
|
```css
|
|
.alpha > .beta + .alpha > .beta {
|
|
order: 2;
|
|
}
|
|
```
|
|
|
|
_this is a different selector than expected as `.beta + .alpha` matches `.beta` followed by `.alpha`._<br>
|
|
_avoid these cases when you disable `:is()`_<br>
|
|
_writing the selector without nesting is advised here_
|
|
|
|
```css
|
|
/* without nesting */
|
|
.alpha > .beta + .beta {
|
|
order: 2;
|
|
}
|
|
```
|
|
|
|
### ⚠️ Spec disclaimer
|
|
|
|
The [CSS Nesting Module] spec states on nesting that "Declarations occurring after a nested rule are invalid and ignored.".
|
|
While we think it makes sense on browsers, enforcing this at the plugin level introduces several constraints that would
|
|
interfere with PostCSS' plugin nature such as with `@mixin`
|
|
|
|
[css-img]: https://cssdb.org/images/badges/nesting-rules.svg
|
|
[css-url]: https://cssdb.org/#nesting-rules
|
|
[discord]: https://discord.gg/bUadyRwkJS
|
|
[npm-img]: https://img.shields.io/npm/v/postcss-nesting.svg
|
|
[npm-url]: https://www.npmjs.com/package/postcss-nesting
|
|
|
|
[CSS Nesting]: https://drafts.csswg.org/css-nesting-1/
|
|
[PostCSS]: https://github.com/postcss/postcss
|
|
[PostCSS Nesting]: https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-nesting
|
|
[Deno]: https://deno.land/x/postcss_nesting
|
|
[PostCSS Nested]: https://github.com/postcss/postcss-nested
|
|
[Sass]: https://sass-lang.com/
|
|
[CSS Nesting Module]: https://www.w3.org/TR/css-nesting-1/
|