postcss-var-replace

PostCSS plugin to replace CSS variables` with their static values.

This plugin provides a future-proof way of using most of CSS variables features, including selector cascading (with some caveats).

Requirements

This package requires an LTS Node version (v18.0.0+)

Install

npm add postcss-var-replace

Usage

For more general PostCSS usage, look here.

import postcss from 'postcss';
import { postcssVarReplace } from 'postcss-var-replace';

const input = `
:root {
	--font-name: 'my-font-family-name';
}

@font-face {
	font-family: var(--font-name);
	src: url('myfont.woff2') format('woff2');
}`;

const { css } = postcss([postcssVarReplace()]).process(input);

console.log(css);

Options

preserve

Type: boolean
Default: false

Allows you to preserve custom properties & var() usage in output.

Possible values:

• false: Removes --var declarations and replaces var() with their resolved/computed values.
• true: Keeps var() declarations in the output and has the computed value as a fallback declaration. Also keeps computed --var declarations.
• 'computed': Keeps computed --var declarations in the output. Handy to make them available to your JavaScript.
• (declaration) => boolean|'computed' : function/callback to programmatically return whether preserve the respective declaration

preserveAtRulesOrder

Type: boolean
Default: false

Keeps your at-rules like media queries in the order to defined them.

Ideally, this would be defaulted to true and it will be in the next major version. All of the tests expecations need to be updated and probably just drop support for preserveAtRulesOrder: false

preserveInjectedVariables

Type: boolean
Default: true

Whether to preserve the custom property declarations inserted via the variables option from final output.

A typical use case is CSS Modules, where you would want to avoid repeating custom property definitions in every module passed through this plugin. Setting this option to false prevents JS-injected variables from appearing in output CSS.

import postcss from 'postcss';
import { postcssVarReplace } from 'postcss-var-replace';

postcss([
  postcssVarReplace({
    variables: {
      '--some-var': '100px',
      '--other-var': {
        value: '#00ff00'
      },
      '--important-var': {
        value: '#ff0000',
        isImportant: true
      }
    }
  })
]).process(css, opts);

variables

Type: object
Default: {}

Define an object map of variables in JavaScript that will be declared at the :root scope.

Can be a simple key-value pair or an object with a value property and an optional isImportant bool property.

The object keys are automatically prefixed with -- (according to CSS custom property syntax) if you do not provide it.

Contributing, Working With This Repo

We 💛 contributions! After all, this is a community-driven project. We have no corporate sponsorship or backing. The maintainers and users keep this project going!

Please check out our Contribution Guide.

Attribution

This is a modern fork of https://github.com/MadLittleMods/postcss-css-variables

License

MIT License