PostCSS plugin to convert HEX, RGB, HSL and keyword colors between themselves (without transform to keyword color format). Uses color-convert under hood. Support Sass(SCSS) (postcss-scss or postcss-sass need) and CSS variables.

$ npm install postcss-color-converter

// dependencies
var fs = require("fs")
var postcss = require("postcss")
var colorConverter = require("postcss-color-converter")

// css to be processed
var css = fs.readFileSync("input.css", "utf8")

// process css
var output = postcss()
  .use(colorConverter({ outputColorFormat: 'rgb' }))
  .process(css)
  .css

More preferable to use it through the PostCSS CLI

npm install postcss-cli --save-dev

Use plugin in your postcss.config.js configuration file:

var colorConverter = require('postcss-color-converter');

module.exports = {
  /* set syntax option, if you use it for scss files */
  syntax: 'postcss-scss',
  plugins: [
    colorConverter(/* pluginOptions */)
  ]
}

Use npm script in package.json, such as:

{
  "scripts": {
    "postcss": "postcss ./src/styles/*.css --config ./postcss.config.js -r"
  }
}

Then:

npm run postcss

Please refer to PostCSS documentation for you current environment.

Type: String
Required
Available values: hex, rgb, hsl
Default: ''
Set output color format. Don't forget set this parameter.

Type: String[]
Available values: hex, rgb, hsl, keyword
Default: []
Array of color formats, which you do not want to convert.

Type: Boolean
Default: false
If true, output RGB and HSL colors will always have alpha chanel value (which will be equal to 1), even if converted from color without alpha chanel. This parameter does not apply to HEX color.
If ignore includes outputColorFormat color format, this parameter will be ignore.

colorConverter({
  outputColorFormat: 'hsl',
  ignore: ['hex'],
  alwaysAlpha: true,
});

Using this input.css and input.scss with option outputColorFormat: 'rgb':

body {
  --blue: blue;
  color: #ef51;
  background-color: #ffffff;
  fill: hsla(56, 69%, 57%, 0.3);
  box-shadow:
    0 0 0 0 #fff,
    10px 10px 0 0 green,
    20px 20px 0 0 #00000080,
    30px 30px 0 0 rgb(123, 123, 123);
}

p {
  $darkRed: #6009;
}

you will get:

body {
  --blue: rgb(0, 0, 255);
  color: rgba(238, 255, 85, 0.07);
  background-color: rgb(255, 255, 255);
  fill: rgba(221, 211, 70, 0.3);
  box-shadow:
    0 0 0 0 rgb(255, 255, 255),
    10px 10px 0 0 rgb(0, 128, 0),
    20px 20px 0 0 rgba(0, 0, 0, 0.5),
    30px 30px 0 0 rgb(123, 123, 123);
}

p {
  $darkRed: rgba(102, 0, 0, 0.6);
}

Checkout tests for more examples or clone this repository and use:

$ npm i
$ npm run postcss

Then go to test/fixtures folder and see common.test.scss file.

This is my first open-source work and my English is not very good, so if you find inaccuracies or errors in the documentation, then let me know. Pull requests are always welcome. Pull requests must be accompanied by passing automated tests ($ npm test). For bugs and feature requests, please create an issue.