🚀 Astro Purgecss

Purgecss helps you remove unused CSS rules from your final astro bundle.

📦 Installation

⚡ Quick Install

the astro add command-line tool automates the installation for you. Run one of the following commands in a new terminal window. (If you aren’t sure which package manager you’re using, run the first command.) Then, follow the prompts, and type “y” in the terminal (meaning “yes”) for each one.

# Using PNPM
pnpm astro add astro-purgecss
# Using NPM
npx astro add astro-purgecss
# Using Yarn
yarn astro add astro-purgecss

🔧 Manual Install

First, install the purgecss & astro-purgecss packages using your package manager. (If you aren’t sure which package manager you’re using, run the first command.)

Using PNPM

pnpm install purgecss astro-purgecss

Using NPM

npm install purgecss astro-purgecss

Using Yarn

yarn add purgecss astro-purgecss

Then, apply this integration to your astro.config.mjs file using the integrations property:

import purgecss from 'astro-purgecss';

export default {
  // ...
  integrations: [purgecss()]
};

Note

To make sure this integration works properly, it's recommended to put purgecss() as the last element in the integrations array.

🥑 Usage

When you install this integration, things will be auto-wired for you. and all your generated css files should be purged from unused classes automagically.

However, there's one small caveat: By default, Astro inlines small CSS files as part of its bundle control. This means that the plugin won't be able to purge CSS rules from those inlined files. To prevent Astro from inlining CSS styles, you can set the inlineStylesheets option to never in your astro.config.mjs file:

export default defineConfig({
+  build: {
+    inlineStylesheets: 'never'
+  }
});

⚙️ Configuration

PurgeCSS has a list of options that allow you to customize its behavior. And this Astro integration allow you to pass those options easily in your astro.config.mjs file:

export default defineConfig({
  integrations: [
    purgecss({
      fontFace: true,
      keyframes: true,
      safelist: ['random', 'yep', 'button', /^nav-/],
      blocklist: ['usedClass', /^nav-/],
      content: [
        process.cwd() + '/src/**/*.{astro,vue}' // Watching astro and vue sources (read SSR docs below)
      ],
      extractors: [
        {
          // Example using a taiwindcss compatible class extractor
          extractor: (content) =>
            content.match(/[^<>"'`\s]*[^<>"'`\s:]/g) || [],
          extensions: ['astro', 'html']
        }
      ]
    })
  ]
});

📖 Available Options

Here is a list of options, that are allowed to be passed in the config:

export type PurgeCSSOptions = {
  fontFace?: boolean; // removes any unused @font-face if set to true
  keyframes?: boolean; // removes unused keyframes by setting if set to true
  rejected?: boolean; // scan through the removed list to see if there's anything wrong
  rejectedCss?: boolean; // keeps the discarded CSS
  variables?: boolean; // removes any unused CSS variables if set to true
  safelist?: UserDefinedSafelist; // indicates which selectors are safe to leave in the final CSS
  blocklist?: StringRegExpArray; // blocks the CSS selectors from appearing in the final output CSS
  content?: Array<string | RawContent>;
  // provides custom functions to extract CSS classes in specific ways (eg. when using tailwind.css)
  extractors?: {
    extractor: (content: string) => string[]; // matched css classes
    extensions: string[]; // file extensions for which this extractor is to be used
  }[];
};

To learn more about the available options, please refer to PurgeCSS official docs.

We have also setup an example repository available here: example-purgecss

🌐 SSR Mode

If you are using Astro SSR in your project, you must add your Astro and framework source files into the content option (see example below). Since the integration analyzes the final client-side build, some SSR-rendered pages might not be included in the initial scan, which could result in necessary CSS being incorrectly purged.

Example configuration for SSR:

export default defineConfig({
  integrations: [
    purgecss({
      content: [
        './src/**/*.{astro,js,jsx,ts,tsx,vue,svelte}'
        // Add any other template files that contain styles
      ]
    })
  ]
});

Important Notes

1. CSS Retention: Due to the integration's file scanning approach, some unused CSS might be retained. This is a deliberate trade-off to prevent accidentally removing dynamically used styles.

2. Inline Styles vs External Stylesheets: The integration can more accurately analyze and purge external stylesheets compared to inline styles embedded within components:

   • ✅ Recommended: Use external stylesheet files (.css)
   • ⚠️ Less Effective: Inline styles in component files

⚠️ Caveats

• Some options are not allowed to be passed in your astro.config.mjs config file, to not interfere with the internals of this integration.

• If you are using Astro view transitions, use the following options so that purgecss keeps the corresponding animations:

export default defineConfig({
  integrations: [
    purgecss({
      keyframes: false,
      safelist: {
        greedy: [
          /*astro*/
        ]
      }
    })
  ]
});

• If you are using tailwind.css, please read about purge limitations in this guide writing-purgeable-html. You may also need a custom class extractor compatible with arbitrary and container based tailwind.css classes. For example:

export default defineConfig({
  integrations: [
    purgecss({
      extractors: [
        {
          extractor: (content) =>
            content.match(/[^<>"'`\s]*[^<>"'`\s:]/g) || [],
          extensions: ['astro', 'html']
        }
      ]
    })
  ]
});

📝 Changelog

Please see the Changelog for more information on what has changed recently.

💝 Acknowledgements

• Purgecss