postcss-prune-var

postcss-prune-var

PostCSS plugin to remove all unused variables in a CSS file.

A --variable is considered unused if it, or any other variables consuming it are not accessed by a single var() statement in the whole CSS file.

This is unsafe if there is a possibility of a second CSS file accessing variables from the first one.

How does it work, and how is it different from postcss-unused-var?

• postcss-unused-var is outdated, deprecated, and didn't work right.
• Treats all variables as global, because they are.
• Removes variables from everywhere, including :root.
• Checks and prevents removal of variables only used by other variables that are accessed with var() by following variable dependency graph.
• At the same time, if a variable is only used by other unused variables, it will also be removed.
• Way faster.

Install

npm install postcss-prune-var --save-dev

Usage

const pruneVar = require('postcss-prune-var');

const yourConfig = {
	plugins: [pruneVar()],
};

Example

Input:

:root {
	--root-unused: red;
	--root-unused-proxy: var(--root-unused);
	--root-used: blue;
}

.foo {
	--unused: red;
	--unused-proxy: var(--unused);
	--proxied: pink;
	--proxy: var(--proxied);
	--used: green;
	color: var(--root-used);
	background: linear-gradient(to bottom, var(--used), var(--proxy));
}

Output

:root {
	--root-used: blue;
}

.foo {
	--proxied: pink;
	--proxy: var(--proxied);
	--used: green;
	color: var(--root-used);
	background: linear-gradient(to bottom, var(--used), var(--proxy));
}