Gatsby Plugin Purgecss

Works with Gatsby v2/v3/v4/v5

What is this plugin about?

Remove unused css from css/sass/less/stylus files and modules in your Gatsby project using purgecss. 🎉. Supports tailwind, bootstrap, bulma etc.

⚠️ NOTE: This is NOT an install and forget type plugin. By default, it may remove required styles too.

Please read Help! Purgecss breaks my site 😯 to make sure gatsby-plugin-purgecss does not cause you issues and TLDR for the important bits

📘 Read the latest docs here. • Changelog - includes migration to v6 guide • Older v5 doc

Demo

When used in gatsby-starter-bootstrap

When used in gatsby-starter-bootstrap-cv (installed by default)

Supported files

• .css , .module.css
• .scss, .sass, .module.scss, .module.sass (via gatsby-plugin-sass)
• .less, .module.less (via gatsby-plugin-less)
• .styl, .module.styl (via gatsby-plugin-stylus)

Installation

npm i gatsby-plugin-purgecss

Usage

Add the plugin AFTER other css/postcss plugins

// gatsby-config.js
module.exports = {
  plugins: [
    `gatsby-plugin-stylus`,
    `gatsby-plugin-sass`,
    `gatsby-plugin-less`,
    `gatsby-plugin-postcss`,
    // Add after these plugins if used
    {
      resolve: `gatsby-plugin-purgecss`,
      options: {
        printRejected: true, // Print removed selectors and processed file names
        // develop: true, // Enable while using `gatsby develop`
        // tailwind: true, // Enable tailwindcss support
        // ignore: ['/ignored.css', 'prismjs/', 'docsearch.js/'], // Ignore files/folders
        // purgeOnly : ['components/', '/main.css', 'bootstrap/'], // Purge only these files/folders
        purgeCSSOptions: {
          // https://purgecss.com/configuration.html#options
          // safelist: ['safelist'], // Don't remove this selector
        },
        // More options defined here https://purgecss.com/configuration.html#options
      },
    },
  ],
};

Read about all the available options.

TLDR

• Define options in gatsby-config.js, not purgecss.config.js.
• If using tailwindcss, use the tailwind: true option.
• Use printRejected: true option to print the removed selectors.
• Only files processed by Webpack will be purged.
• my-selector will not match mySelector.
• Whitelist required selectors or ignore files/folder using the Whitelist Solutions guide.
• Ignore complete packages with ignore: ['packagename/'].
• To only purge specific files/packages use purgeOnly: ['fileOrPackage/'].
• Only js, jsx, ts, tsx files are scanned for selectors by default. If you want to add md or mdx use content: [path.join(process.cwd(), 'src/**/!(*.d).{ts,js,jsx,tsx,md,mdx}')] or better, just whitelist the required selectors.
• Tailwind now can use purgecss directly too so you may want to use that. This plugin has the benefit of being able to define more options (ignore, purgeOnly, printRejected etc.) and can purge CSS modules.

Help! Purgecss breaks my site

Diagnosing the issue

• Use printRejected: true option which will print the filenames and the selectors which were removed.
• Identify which of the required selectors were removed.
• Whitelist the required selectors or completely ignore files using Whitelist Solutions guide.
• Look at the Issues section to understand why/how the purge was performed.

Issues

This section documents purgecss behavior in removing unused css. Most of the rules apply in any project and is not gatsby-plugin-purgecss specific.

Issue 1: CSS file not getting purged

For gatsby-plugin-purgecss to work on a css file it must be imported by a script file inside your src folder. This plugin depends on webpack to process css. If webpack does not use the css file then gatsby-plugin-purgecss cannot process it.

Also, make sure that you included the plugin after sass/less/stylus/postcss plugins.

Issue 2: Selectors with dashes in name gets removed when used with named imports

For eg: style.css

.my-selector {
  color: 'white';
}

index.js

// Named import
import style from './style.css';
...
<div className={style.mySelector} /> ❌

Here .my-selector will get removed since purgecss by default cannot match it with mySelector.

Read how to solve this issue in the “Whitelist Solutions” section.

Note: Directly importing and using the selector name as is will work as intended

import './style.css';
<div className={`my-selector`} /> ✅

Issue 3: Styles getting purged even though the script file has selector names

Make sure that the script file is in the src folder.
If you want to look for selectors in another folder, use the content option.

Issue 4: Getting “Could not parse file, skipping. Your build will not break.”

If you use postcss syntax based plugins then read this.

Something is wrong. Good news is gatsby-plugin-purgecss should not cause any issue in such cases, files which could not be parsed will be skipped. If you want to diagnose the problem then use the debug option. Also, feel free to create a GitHub issue.

Issue 5: Using npm packages with components which import css files

If you import a npm package which imports its own styles locally, then gatsby-plugin-purgecss will incorrectly remove all the css imported by the package. It’s because by default the selectors are only matched with the files under ‘src’ folder.
To get around this, you could:

1. Ignore the file completely using the ignore option
2. Whitelist the required selectors as described in the next section.
3. Use the content option and add the package’s path. Eg:

content: [
  path.join(process.cwd(), 'src/**/!(*.d).{ts,js,jsx,tsx}'),
  path.join(process.cwd(), 'node_modules/my-npm-package/folder-to-match/!(*.d).{ts,js,jsx,tsx}')
];

Issue 6: Works in develop, breaks in build

gatsby-plugin-purgecss by default does not run when using gatsby develop.

Issue 7: Selectors in markdown (.md, .mdx) files are getting removed

Markdown files are not scanned for selectors by default. Use the content option. to add them.

content: [path.join(process.cwd(), 'src/**/!(*.d).{ts,js,jsx,tsx,md,mdx}')]

Note: This may decrease the amount of styles removed because purgecss will consider every word in the markdown file to be a selector.
If possible, just whitelist the required selectors instead of using this option.

Whitelist Solutions

You can use any of these techniques to stop purgecss from removing required styles

1. Whitelist the selector using the safelist option in gatsby-config.js

purgeCSSOptions: {
  safelist: ['my-selector'], // Don't remove this selector
}

PurgeCSS docs.
Read about safelist option.

2. Use a JavaScript comment

// my-selector
<div className={style.mySelector} />

This comment can be in any script file inside src.

3. Use Regex pattern to exclude many selectors

safelist option is available from purgecss

purgeCSSOptions: {
  safelist: [/^btn/], // Don't remove this selector
}

4. Use purgecss ignore comment in css file

/* purgecss ignore */
.my-selector {
  color: 'white';
}

This comment will ignore the selector on the next line.

5. Use purgecss ignore block comments in css file

/* purgecss start ignore */
button {
  color: 'white';
}
.yo {
  color: 'blue';
}
/* purgecss end ignore */

This comment pair will ignore all css selectors between them.

6. Ignore files and folder using the ignore options

ignore: [
  'ignoredFile.css',
  'ignoredFolder/',
  'sub/folder/ignore/',
  'inFolder/file.css',
];

Note: always use forward slash / for folders, even on Windows.
Read about ignore option.

7. Purge only specified files and skip everything else

purgeOnly: ['/mainstyles.css', 'node_modules/bootstrap'];

Note: always use forward slash / for folders, even on Windows.
Good if you only need to purge some large css library and not touch anything else.
Read about purgeOnly option.

8. For selector with dashes in them and using named imports

You could write it like className={style['my-selector']} instead.

Improving Purgecss selector detection

Purgecss relies on extractors to get the list of selector used in a file. The default extractor considers every word of a file as a selector. You could use your own extractor (or get one made by other community members) to improve detection and further decrease your css file size. Read more at Purgecss docs.

If you do find/write a better extractor suited for Gatsby, please help me add it to the docs.

Important Notes

Running

By default, this plugin only runs when building the project (gatsby build).
It will print the amount of css removed. To run it while using gatsby develop, use the develop: true option.

Size reporting

The size reported by this plugin is the approximate size of the css content before any optimizations have been performed.
The actual file size should be smaller.

Selector matching

This plugin loads css files (or transformed output from css plugins) and searches for matching selectors in js, jsx, ts, tsx files in src/. It does not know which css file belongs to which source file. Therefore, for eg., if there is a class .module in some css file, it will not be removed if it used in any script file under src/.

Safelist [‘html’, ‘body’]

Since html and body tags do not appear in src/ files, it is safelisted by default to not be removed.

Webpack loader order

Sass/Less/Stylus(or any other loader) -> PostCSS -> PurgeCSS -> CSSLoader -> (CSSExtract/StyleLoader)
Note: Sass/Less/Stylus @imports are executed before this plugin, therefore, it won’t see the @imported files as separate files.

Options

Options can be specified in your gatsby-config.js file like so:

module.exports = {
  plugins: [
    {
      resolve: 'gatsby-plugin-purgecss',
      options: {
        printRejected: true,
        purgeCSSOptions: {
          safelist: [],
        },
      },
    },
  ],
};

Purgecss options can be specified under the purgeCSSOptions key.

Read about all the purgecss options

printRejected

Print the list of removed selectors
printRejected: boolean

printRejected: true;

It will print maximum of 100 removed selector per file to keep the output readable.
To view all the removed selector enable the printAll option.
default: false

printAll

Enables printRejected to print all the rejected selectors.
(Output can get messy)
printAll: boolean

printAll: true;

Needs printRejected option to be true.
default: false

purgeOnly

Only purge these files/folders.
ignore: Array<string>

purgeOnly: ['/main.css', 'bootstrap/', 'node_modules/font-awesome/'];

Note: always use forward slash / for folders, even on Windows.
Can be combined with the ignore option.
default: []

ignore

Stop these files or folders from getting purged.
ignore: Array<string>

ignore: [
  '/ignoredFile.css',
  'ignoredFolder/',
  'sub/folder/ignore/',
  'inFolder/file.css',
];

Note: always use forward slash / for folders, even on Windows.
default: []

tailwind

Enable Tailwind support.

Tailwind now can use purgecss directly too so you may want to use that. This plugin has the benefit of being able to define more options (ignore, purgeOnly, printRejected etc.) and can purge CSS modules.

tailwind: boolean

tailwind: true;

Uses extractors needed for parsing tailwind class names.
Enable if you are using tailwindcss.
default: false

develop

Enable plugin while using gatsby develop.
develop: boolean

develop: true;

This does not print the total css removed.
To see what is being removed, use it with the printRejected option.
default: false

debug

Enable debugging
debug: boolean

debug: true;

It will write two files to disk.
gatsby-plugin-purgecss-debug-config.js with Gatsby’s webpack config.
gatsby-plugin-purgecss-debug.js with the errors encountered.
default: false

printSummary

Print the total removed css stats.
printSummary: boolean

printSummary: true;

default: true

safelist - from purgecss

Stops from removing these selectors.
safelist: Array<string>

purgeCSSOptions: {
  safelist: ['my-selector', 'footer'];
}

More options for safelist

Note: do NOT add . or # for classes and ids.
'html', 'body' are always safelisted.
Since v2.3.0 manually including ‘html’, ‘body’ is no longer required.
default: []

content - from purgecss

Files to search for selectors.
content: Array<string>

purgeCSSOptions: {
  content: [
    path.join(process.cwd(), 'src/**/!(*.d).{ts,js,jsx,tsx}'),
    path.join(process.cwd(), 'anotherFolder/!(*.d).{ts,js,jsx,tsx}'),
  ];
}

default: [path.join(process.cwd(), 'src/**/!(*.d).{ts,js,jsx,tsx}')]

Other options from purgecss

Read about other purgecss options.

Versioning

gatsby-plugin-purgecss uses SemVer for versioning.

Acknowledgment

This project was made possible due to the incredible work done on the following projects:

• purgecss
• purgecss-loader
• gatsby

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

Hey 👋 If my packages has helped you in any way, consider making a small donation to encourage me to keep contributing. Maintaining good software takes time and effort and for open source developers there is very less incentives to do so. Your contribution is greatly appreciated and will motivate me to continue to support developing my packages which you may have used.