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css-has-pseudo

1.0.0 • Public • Published

CSS Has Pseudo

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CSS Has Pseudo lets you style elements relative to other elements in CSS, following the Selectors Level 4 specification.

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(h1h2h3h4h5h6){
  /* 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:

npx css-has-pseudo SOURCE.css TRANSFORMED.css

Next, use your transformed CSS with this script:

<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, the script will work down to Internet Explorer 9.

How it works

The PostCSS plugin clones rules containing :has, replacing them with an alternative [:has] selector.

body:has(:focus{
  background-color: yellow;
}
 
section:not(:has(h1h2h3h4h5h6){
  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(h1h2h3h4h5h6){
  background-color: gray;
}

Next, the JavaScript library adds a [:has] attribute to elements otherwise matching :has natively.

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

install

npm i css-has-pseudo

Downloadsweekly downloads

1,010,486

version

1.0.0

license

CC0-1.0

homepage

github.com

repository

Gitgithub

last publish

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