PostCSS Custom Selectors lets you use Custom Selectors in CSS, following the CSS Extensions specification.
@custom-selector :--heading h1, h2, h3;
article :--heading + p {
margin-top: 0;
}
/* becomes */
article h1 + p, article h2 + p, article h3 + p {}
Usage
Add PostCSS Custom Selectors to your project:
npm install postcss-custom-selectors --save-dev
Use PostCSS Custom Selectors to process your CSS:
const postcssCustomSelectors = require('postcss-custom-selectors');
postcssCustomSelectors.process(YOUR_CSS /*, processOptions, pluginOptions */);
Or use it as a PostCSS plugin:
const postcss = require('postcss');
const postcssCustomSelectors = require('postcss-custom-selectors');
postcss([
postcssCustomSelectors(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);
PostCSS Custom Selectors runs in all Node environments, with special instructions for:
Node | PostCSS CLI | Webpack | Create React App | Gulp | Grunt |
---|
Options
preserve
The preserve
option determines whether custom selectors and rules using
custom selectors should be preserved in their original form.
@custom-selector :--heading h1, h2, h3;
article :--heading + p {
margin-top: 0;
}
/* becomes */
article h1 + p, article h2 + p, article h3 + p {}
article :--heading + p {}
importFrom
The importFrom
option specifies sources where custom selectors can be
imported from, which might be CSS, JS, and JSON files, functions, and directly
passed objects.
postcssCustomSelectors({
importFrom: 'path/to/file.css' // => @custom-selector :--heading h1, h2, h3;
});
article :--heading + p {
margin-top: 0;
}
/* becomes */
article h1 + p, article h2 + p, article h3 + p {}
Multiple sources can be passed into this option, and they will be parsed in the
order they are received. JavaScript files, JSON files, functions, and objects
will need to namespace custom selectors using the customProperties
or
custom-properties
key.
postcssCustomSelectors({
importFrom: [
'path/to/file.css',
'and/then/this.js',
'and/then/that.json',
{
customSelectors: { ':--heading': 'h1, h2, h3' }
},
() => {
const customProperties = { ':--heading': 'h1, h2, h3' };
return { customProperties };
}
]
});
exportTo
The exportTo
option specifies destinations where custom selectors can be
exported to, which might be CSS, JS, and JSON files, functions, and directly
passed objects.
postcssCustomSelectors({
exportTo: 'path/to/file.css' // @custom-selector :--heading h1, h2, h3;
});
Multiple destinations can be passed into this option, and they will be parsed
in the order they are received. JavaScript files, JSON files, and objects will
need to namespace custom selectors using the customProperties
or
custom-properties
key.
const cachedObject = { customSelectors: {} };
postcssCustomSelectors({
exportTo: [
'path/to/file.css', // @custom-selector :--heading h1, h2, h3;
'and/then/this.js', // module.exports = { customSelectors: { ':--heading': 'h1, h2, h3' } }
'and/then/this.mjs', // export const customSelectors = { ':--heading': 'h1, h2, h3' } }
'and/then/that.json', // { "custom-selectors": { ":--heading": "h1, h2, h3" } }
cachedObject,
customProperties => {
customProperties // { ':--heading': 'h1, h2, h3' }
}
]
});