> For the complete documentation index, see [llms.txt](https://bryan-guner.gitbook.io/my-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bryan-guner.gitbook.io/my-docs/redux/repos/examples/real-world/node_modules/css-has-pseudo.md).

# CSS Has Pseudo

[![NPM Version](https://img.shields.io/npm/v/css-has-pseudo.svg)](https://www.npmjs.com/package/css-has-pseudo) [![Build Status](https://img.shields.io/travis/csstools/css-has-pseudo/master.svg)](https://travis-ci.org/csstools/css-has-pseudo) [![Support Chat](https://img.shields.io/badge/support-chat-blue.svg)](https://gitter.im/postcss/postcss)

[CSS Has Pseudo](https://github.com/csstools/css-has-pseudo) lets you style elements relative to other elements in CSS, following the [Selectors Level 4](https://drafts.csswg.org/selectors-4/#has-pseudo) specification.

```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 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/browser"></script>
<script>cssHasPseudo(document)</script>
```

That’s it. The script is 765 bytes and works in all browsers, including Internet Explorer 11. With a [Mutation Observer polyfill](https://github.com/webmodules/mutation-observer), the script will work down to Internet Explorer 9.

## How it works

The [PostCSS plugin](https://github.com/bgoonz/Learning-Redux/blob/master/repos/examples/real-world/node_modules/css-has-pseudo/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](https://github.com/bgoonz/Learning-Redux/blob/master/repos/examples/real-world/node_modules/css-has-pseudo/README-BROWSER.md) adds a `[:has]` attribute to elements otherwise matching `:has` natively.

```html
<body :has(:focus)>
  <input value="This element is focused">
</body>
```
