vite-plugin-tailwind-purgecss

Important

This plugin will no longer be necessary after the release of Tailwind v4 as they will introduce a new Vite plugin that will detect and generate the classes based on the module graph! As such, this plugin will only support Tailwind v3.

A simple vite plugin that thoroughly purges excess CSS using PurgeCSS. This package should be used in combination with Tailwind and a Tailwind UI component library such as Skeleton or Flowbite.

⚠ Notice ⚠

This package is still very experimental. Breaking changes can occur at any time. We'll stabilize once we hit a 1.0.0 release.

Motivation

Tailwind UI component libraries are fantastic and are a joy to work with, but they come with an important caveat. The downside to them is that all of the Tailwind classes that are used in their provided components are always generated, even if you don't import and use any of their components. This leads to a larger than necessary CSS bundle.

This is a limitation of how Tailwind works with it's content field in its config. Tailwind searches through all of the files that are specified in content, uses a regex to find any possible selectors, and generates their respective classes. There's no treeshaking and no purging involved.

Why not use `postcss-purgecss` or `rollup-plugin-purgecss`?

PurgeCSS provides a suite of plugins that do a well enough job for most projects. However, plugins such as postcss-purgecss and rollup-plugin-purgecss take a rather naive approach to selector extraction. Just like how Tailwind generates its classes, they only analyze the content and files that are passed to them through their content fields, which means that if you pass a UI library to it, none of the selectors that are unused in your project will be properly purged.

How it works

Ideally, we'd like to keep the selectors that are only being used in your project. We accomplish by analyzing the emitted JS chunks that are generated by Rollup, which only include the modules that are actually used in your project, and extracting out any of their possible selectors. From there, we can pass along the selectors to PurgeCSS for final processing.

Using vite-plugin-tailwind-purgecss with Skeleton, we're able to reduce the CSS bundle size of Skeleton's Barebones Template from:

92.50 kB │ gzip: 12.92 kB

down to:

27.29 kB │ gzip: 5.40 kB

Usage

Installation

npm i -D vite-plugin-tailwind-purgecss

Add to Vite

// vite.config.ts
import { purgeCss } from 'vite-plugin-tailwind-purgecss';

const config: UserConfig = {
	plugins: [sveltekit(), purgeCss()],
};

Safelisting

If selectors that shouldn't be purged are being removed, simply add them to the safelist.

// vite.config.ts
import { purgeCss } from 'vite-plugin-tailwind-purgecss';

const config: UserConfig = {
	plugins: [
		sveltekit(),
		purgeCss({
			safelist: {
				// any selectors that begin with "hljs-" will not be purged
				greedy: [/^hljs-/],
			},
		}),
	],
};

Alternatively, if you'd like to safelist selectors directly in your stylesheets, you can do so by adding special comments:

/*! purgecss start ignore */

h1 {
	color: red;
}

h2 {
	color: blue;
}

/*! purgecss end ignore */

You can also safelist selectors directly in the declaration block as well:

h3 {
	/*! purgecss ignore current */
	color: pink;
}

For further configuration, you can learn more here.

AdrianGonz97/vite-plugin-tailwind-purgecss