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postcss-custom-properties
Advanced tools
Package description
The postcss-custom-properties npm package is a PostCSS plugin that allows you to use CSS Custom Properties (also known as CSS variables) in environments that do not support them natively. It transforms CSS variables into static values based on your configurations, making it easier to maintain themes and styles dynamically across your project.
Transform CSS Custom Properties
This feature allows the transformation of CSS custom properties into their corresponding static values. It is useful for supporting older browsers that do not understand CSS variables.
/* Input CSS */
:root {
--main-color: red;
}
a {
color: var(--main-color);
}
/* Output CSS */
a {
color: red;
}
Preserve option
With the preserve option set to true, the plugin outputs both the transformed static value and the original variable. This is useful for progressive enhancement.
/* Input CSS */
:root {
--main-color: red;
}
a {
color: var(--main-color);
}
/* Output CSS with preserve: true */
a {
color: red;
color: var(--main-color);
}
cssnext is a PostCSS plugin that allows you to use future CSS features today. It includes support for CSS custom properties among other features. Compared to postcss-custom-properties, cssnext offers a broader range of CSS features but might be heavier due to its comprehensive nature.
postcss-preset-env lets you convert modern CSS into something most browsers can understand, determining the polyfills you need based on your targeted browsers or runtime environments. It includes handling of CSS custom properties as part of its feature set, similar to postcss-custom-properties, but is more configurable and includes various stages of CSS specifications.
Readme
PostCSS Custom Properties lets you use Custom Properties in CSS, following the CSS Custom Properties specification.
:root {
--color: red;
}
h1 {
color: var(--color);
}
/* becomes */
:root {
--color: red;
}
h1 {
color: red;
color: var(--color);
}
Note: This plugin only processes variables that are defined in the :root
selector.
Add PostCSS Custom Properties to your project:
npm install postcss-custom-properties --save-dev
Use PostCSS Custom Properties as a PostCSS plugin:
const postcss = require('postcss');
const postcssCustomProperties = require('postcss-custom-properties');
postcss([
postcssCustomProperties(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);
PostCSS Custom Properties runs in all Node environments, with special instructions for:
Node | PostCSS CLI | Webpack | Create React App | Gulp | Grunt |
---|
The preserve
option determines whether Custom Properties and properties using
custom properties should be preserved in their original form. By default, both
of these are preserved.
postcssCustomProperties({
preserve: false
});
:root {
--color: red;
}
h1 {
color: var(--color);
}
/* becomes */
h1 {
color: red;
}
The importFrom
option specifies sources where Custom Properties can be imported
from, which might be CSS, JS, and JSON files, functions, and directly passed
objects.
postcssCustomProperties({
importFrom: 'path/to/file.css' // => :root { --color: red }
});
h1 {
color: var(--color);
}
/* becomes */
h1 {
color: red;
}
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 Properties using the customProperties
or
custom-properties
key.
postcssCustomProperties({
importFrom: [
'path/to/file.css', // :root { --color: red; }
'and/then/this.js', // module.exports = { customProperties: { '--color': 'red' } }
'and/then/that.json', // { "custom-properties": { "--color": "red" } }
{
customProperties: { '--color': 'red' }
},
() => {
const customProperties = { '--color': 'red' };
return { customProperties };
}
]
});
See example imports written in CSS, JS, and JSON.
The overrideImportFromWithRoot
option determines if properties added via importFrom
are overridden by properties that exist in :root
.
Defaults to false
.
postcssCustomProperties({
overrideImportFromWithRoot: true
});
The exportTo
option specifies destinations where Custom Properties can be exported
to, which might be CSS, JS, and JSON files, functions, and directly passed
objects.
postcssCustomProperties({
exportTo: 'path/to/file.css' // :root { --color: red; }
});
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 Properties using the customProperties
or
custom-properties
key.
const cachedObject = { customProperties: {} };
postcssCustomProperties({
exportTo: [
'path/to/file.css', // :root { --color: red; }
'and/then/this.js', // module.exports = { customProperties: { '--color': 'red' } }
'and/then/this.mjs', // export const customProperties = { '--color': 'red' } }
'and/then/that.json', // { "custom-properties": { "--color": "red" } }
'and/then/that.scss', // $color: red;
cachedObject,
customProperties => {
customProperties // { '--color': 'red' }
}
]
});
See example exports written to CSS, JS, MJS, JSON and SCSS.
Silence the deprecation notice that is printed to the console when using importFrom
or exportTo
.
"importFrom" and "exportTo" will be removed in a future version of postcss-custom-properties. Check the discussion on github for more details. https://github.com/csstools/postcss-plugins/discussions/192
FAQs
Use Custom Properties Queries in CSS
The npm package postcss-custom-properties receives a total of 5,050,168 weekly downloads. As such, postcss-custom-properties popularity was classified as popular.
We found that postcss-custom-properties demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 5 open source maintainers collaborating on the project.
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Streamline your login process and enhance security by enabling Single Sign-On (SSO) on the Socket platform, now available for all customers on the Enterprise plan, supporting 20+ identity providers.
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