PostCSS color variable shorthand

Introduction

PostCSS plugin that expands color variables to make it quicker to define reusable CSS color variables.

By adding a --hsl or --rgb suffix (See example usage below) to the variable name, this plugin will automatically expand one line of CSS into two. This is useful in case you want to use the same color for hsla().

Usecase

You have defined a bunch of colors in your existig stylesheet, but then later on you want to use the same colors with alpha, or you have just gotten tired of HEX and RGB and want to use HSL instead.

/* Starting point */
--bakground-color: rgb(240, 240, 240);
--text-color: #446677;

/* To get this working _without_ this plugin, you would have to delete most
 * of what you already have, write six new lines of CSS and also figure out
 * what #446677 is in RGB.
 */
--background-color-vars: 240, 240, 240;
--bakground-color: rgb(--background-color-vars);
--bakground-color-alpha: rgba(--background-color-vars, 0.9);
--text-color-vars: 68, 102, 183;
--text-color: rgb(--text-color-vars);
--text-color-alpha: rgba(--text-color-vars, 0.7);

/* To get this working _with_ this plugin, you only need to add "--hsl" at the
 * end of the existing variable names and define the two new "-alpha" colors.
 */
--bakground-color--hsl: rgb(240, 240, 240);
--text-color--hsl: #446677;
--bakground-color-alpha: hsla(--background-color--hsl, 0.9);
--text-color-alpha: hsla(--text-color--hsl, 0.7);

Example

Example input

:root {
  --grey-hue: 205;
  --text-color--hsl: hsl(var(--grey-hue), 20%, 94%);
  --black--hsl: #040404;
}

Example output

:root {
  --grey-hue: 205;
  --text-color--hsl: var(--grey-hue), 20%, 94%;
  --text-color: hsl(var(--text-color--hsl));
  --black--hsl: 0, 0%, 1.569%;
  --black: hsl(var(--black--hsl));
}

Usage

The example usage below will produce the "hsl" output above, but colorSpace can also be "rgb" if you prefer that over "hsl".

import postcssColorVariableShorthand from 'postcss-color-variable-shorthand';

const config = {
  plugins: [
    postcssColorVariableShorthand({colorSpace: 'hsl'}),
  ],
};

export default config;

See PostCSS docs for examples for your environment.

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MIT © Jan Henning Thorsen