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 plugin to transform W3C CSS Custom Properties for cascading variables syntax to more compatible CSS.
N.B. For now the transformation is not complete. It currently just aims to provide a future-proof way of using a limited subset of the features provided by native CSS variables.
Checkout opened issue to know the state of this plugin.
Why not postcss-vars ? Because there is already a plugin with this name that have severals bugs & untested code.
But I look forward to merge those 2 plugins & deprecate this one (see opened issue).
$ npm install postcss-custom-properties
// dependencies
var fs = require("fs")
var postcss = require("postcss")
var customProperties = require("postcss-custom-properties")
// css to be processed
var css = fs.readFileSync("input.css", "utf8")
// process css using postcss-custom-properties
var output = postcss()
.use(customProperties())
.process(css)
.css
Using this input.css:
:root {
--color: red;
}
div {
color: var(--color);
}
you will get:
div {
color: red;
}
Checkout tests for more.
preserve (default: false)Allow you to preserve custom properties & var() usage in output.
var out = postcss()
.use(customProperties({preserve: true}))
.process(css)
.css
variables (default: {})Allow you to pass an object of variables
Work on a branch, install dev-dependencies, respect coding style & run tests before submitting a bug fix or a feature.
$ git clone https://github.com/postcss/postcss-custom-properties.git
$ git checkout -b patch-1
$ npm install
$ npm test
FAQs
Use Custom Properties Queries in CSS
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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