# CSS Has Pseudo [<img src="http://jonathantneal.github.io/js-logo.svg" alt="" width="90" height="90" align="right">][CSS Has Pseudo]
[![NPM Version][npm-img]][npm-url]
[<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord]
[CSS Has Pseudo] lets you style elements relative to other elements in CSS,
following the [Selectors Level 4] specification.
[](https://caniuse.com/#feat=css-has)
```css
a:has(> img) {
/* style links that contain an image */
}
h1:has(+ p) {
/* style level 1 headings that are followed by a paragraph */
}
section:not(:has(h1, h2, h3, h4, h5, h6)) {
/* style sections that don’t contain any heading elements */
}
body:has(:focus) {
/* style the body if it contains a focused element */
}
```
## Usage
From the command line, transform CSS files that use `:has` selectors:
```bash
npx css-has-pseudo SOURCE.css --output TRANSFORMED.css
```
Next, use your transformed CSS with this script:
```html
<link rel="stylesheet" href="TRANSFORMED.css">
<script src="https://unpkg.com/css-has-pseudo/dist/browser-global.js"></script>
<script>cssHasPseudo(document)</script>
```
⚠️ Please use a versioned url, like this : `https://unpkg.com/css-has-pseudo@3.0.0/dist/browser-global.js`
Without the version, you might unexpectedly get a new major version of the library with breaking changes.
⚠️ If you were using an older version via a CDN, please update the entire url.
The old URL will no longer work in a future release.
That’s it. The script is 765 bytes and works in most browser versions, including
Internet Explorer 11. With a [Mutation Observer polyfill], the script will work
down to Internet Explorer 9.
See [README BROWSER](README-BROWSER.md) for more information.
## How it works
The [PostCSS plugin](README-POSTCSS.md) clones rules containing `:has`,
replacing them with an alternative `[:has]` selector.
```css
body:has(:focus) {
background-color: yellow;
}
section:not(:has(h1, h2, h3, h4, h5, h6)) {
background-color: gray;
}
/* becomes */
body[\:has\(\:focus\)] {
background-color: yellow;
}
body:has(:focus) {
background-color: yellow;
}
section[\:not-has\(h1\,\%20h2\,\%20h3\,\%20h4\,\%20h5\,\%20h6\)] {
background-color: gray;
}
section:not(:has(h1, h2, h3, h4, h5, h6)) {
background-color: gray;
}
```
Next, the [JavaScript library](README-BROWSER.md) adds a `[:has]` attribute to
elements otherwise matching `:has` natively.
```html
<body :has(:focus)>
<input value="This element is focused">
</body>
```
[discord]: https://discord.gg/bUadyRwkJS
[npm-img]: https://img.shields.io/npm/v/css-has-pseudo.svg
[npm-url]: https://www.npmjs.com/package/css-has-pseudo
[CSS Has Pseudo]: https://github.com/csstools/postcss-plugins/tree/main/plugins/css-has-pseudo
[Mutation Observer polyfill]: https://github.com/webmodules/mutation-observer
[Selectors Level 4]: https://drafts.csswg.org/selectors-4/#has-pseudo