PostCSS Custom Media
PostCSS Custom Media lets you define @custom-media
in CSS following the Custom Media Specification.
@custom-media --small-viewport (max-width: 30em);
@media (--small-viewport) {
/* styles for small viewport */
}
/* becomes */
@media (max-width: 30em) {
/* styles for small viewport */
}
Usage
Add PostCSS Custom Media to your project:
npm install postcss postcss-custom-media --save-dev
Use it as a PostCSS plugin:
const postcss = require('postcss');
const postcssCustomMedia = require('postcss-custom-media');
postcss([
postcssCustomMedia(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);
PostCSS Custom Media 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 the original notation
is preserved. By default, it is not preserved.
postcssCustomMedia({ preserve: true })
@custom-media --small-viewport (max-width: 30em);
@media (--small-viewport) {
/* styles for small viewport */
}
/* becomes */
@custom-media --small-viewport (max-width: 30em);
@media (max-width: 30em) {
/* styles for small viewport */
}
@media (--small-viewport) {
/* styles for small viewport */
}
importFrom
The importFrom
option specifies sources where custom media can be imported
from, which might be CSS, JS, and JSON files, functions, and directly passed
objects.
postcssCustomMedia({
importFrom: 'path/to/file.css' // => @custom-selector --small-viewport (max-width: 30em);
});
@media (max-width: 30em) {
/* styles for small viewport */
}
@media (--small-viewport) {
/* styles for small viewport */
}
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 media using the customMedia
or
custom-media
key.
postcssCustomMedia({
importFrom: [
'path/to/file.css',
'and/then/this.js',
'and/then/that.json',
{
customMedia: { '--small-viewport': '(max-width: 30em)' }
},
() => {
const customMedia = { '--small-viewport': '(max-width: 30em)' };
return { customMedia };
}
]
});
exportTo
The exportTo
option specifies destinations where custom media can be exported
to, which might be CSS, JS, and JSON files, functions, and directly passed
objects.
postcssCustomMedia({
exportTo: 'path/to/file.css' // @custom-media --small-viewport (max-width: 30em);
});
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 media using the customMedia
or
custom-media
key.
const cachedObject = { customMedia: {} };
postcssCustomMedia({
exportTo: [
'path/to/file.css', // @custom-media --small-viewport (max-width: 30em);
'and/then/this.js', // module.exports = { customMedia: { '--small-viewport': '(max-width: 30em)' } }
'and/then/this.mjs', // export const customMedia = { '--small-viewport': '(max-width: 30em)' } }
'and/then/that.json', // { "custom-media": { "--small-viewport": "(max-width: 30em)" } }
cachedObject,
customMedia => {
customMedia // { '--small-viewport': '(max-width: 30em)' }
}
]
});