PostCSS Random Function

npm install @csstools/postcss-random-function --save-dev

PostCSS Random Function lets you use the random function, following the CSS Values 5 specification.

div {
	color: oklch(0.7, 0.2, random(120deg, 240deg));
}

div {
	color: oklch(0.7, 0.2, random(120deg, 240deg, by 7deg));
}

div {
	color: oklch(0.7, 0.2, random(--text, 120deg, 240deg));
	border-color: oklch(0.7, 0.2, random(--border, 120deg, 240deg));
}

/* becomes */

div {
	color: oklch(0.7, 0.2, 238.66036deg);
}

div {
	color: oklch(0.7, 0.2, 134deg);
}

div {
	color: oklch(0.7, 0.2, 226.47057deg);
	border-color: oklch(0.7, 0.2, 157.76966deg);
}

[!NOTE] Generated values are deterministic pseudo random numbers. Generating values twice with the same input will give the same result. The input length of the CSS source file is used as a random seed.

Usage

Add PostCSS Random Function to your project:

npm install postcss @csstools/postcss-random-function --save-dev

Use it as a PostCSS plugin:

const postcss = require('postcss');
const postcssRandomFunction = require('@csstools/postcss-random-function');

postcss([
	postcssRandomFunction(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);

⚠️ About custom properties

Given the dynamic nature of custom properties it's impossible to know what the variable value is, which means the plugin can't compute a final value for the stylesheet.

Because of that, any usage that contains a var is skipped.

Options

preserve

The preserve option determines whether the original notation is preserved. By default, it is not preserved.

postcssRandomFunction({ preserve: true })

div {
	color: oklch(0.7, 0.2, random(120deg, 240deg));
}

div {
	color: oklch(0.7, 0.2, random(120deg, 240deg, by 7deg));
}

div {
	color: oklch(0.7, 0.2, random(--text, 120deg, 240deg));
	border-color: oklch(0.7, 0.2, random(--border, 120deg, 240deg));
}

/* becomes */

div {
	color: oklch(0.7, 0.2, 238.66036deg);
	color: oklch(0.7, 0.2, random(120deg, 240deg));
}

div {
	color: oklch(0.7, 0.2, 134deg);
	color: oklch(0.7, 0.2, random(120deg, 240deg, by 7deg));
}

div {
	color: oklch(0.7, 0.2, 226.47057deg);
	color: oklch(0.7, 0.2, random(--text, 120deg, 240deg));
	border-color: oklch(0.7, 0.2, 157.76966deg);
	border-color: oklch(0.7, 0.2, random(--border, 120deg, 240deg));
}