# Next.js

Next.js is a React framework for production grade applications that scale. The world's leading companies use Next.js to build server-rendered applications, static websites, and more.

You can use PurgeCSS with Next.js by using the postCSS plugin in the Next.js configuration

# Customize PostCSS configuration (Next.js >= 9.3)

To customize the PostCSS configuration, create a postcss.config.json file in the root of your project.

Add PurgeCSS to the default configuration:

{
  "plugins": [
    "postcss-flexbugs-fixes",
    [
      "postcss-preset-env",
      {
        "autoprefixer": {
          "flexbox": "no-2009"
        },
        "stage": 3,
        "features": {
          "custom-properties": false
        }
      }
    ],
    [
    '@fullhuman/postcss-purgecss',
    {
        content: [
            './pages/**/*.{js,jsx,ts,tsx}',
            './components/**/*.{js,jsx,ts,tsx}'
        ],
        defaultExtractor: content => content.match(/[\w-/:]+(?<!:)/g) || []
    }
],
  ]
}
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# Next.js plugin (Next.js < 9.3)

# Intallation

next-purgecss requires one of the following css next plugins :

Just pick the one that fits your needs. In the following steps, I will use next-css but it works the same for the other css next plugins.

For example, install next-css and next-purgecss :

yarn add @zeit/next-css next-purgecss --dev
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or with npm :

npm install @zeit/next-css next-purgecss --save-dev
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Once you installed the packages, you need to edit next.config.js.

// next.config.js
const withCss = require("@zeit/next-css");
const withPurgeCss = require("next-purgecss");

module.exports = withCss(withPurgeCss());
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# Options

# purgeCssEnabled

By default, next-purgecss will always remove unused CSS, regardless of build environment. You can change that by defining a function for the purgeCssEnabled option. The purgeCssEnabled function receives two arguments:

Argument Type Description
dev Boolean true in development mode (running next) or false in production mode (running next start)
isServer Boolean true during server side compilation or false during client side compilation
// next.config.js
module.exports = withCss(
  withPurgeCss({
    purgeCssEnabled: ({ dev, isServer }) => !dev && !isServer, // Only enable PurgeCSS for client-side production builds
  })
);
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# purgeCssPaths

By default, this plugin will scan components and pages directories for classnames. You can change that by defining purgeCssPaths.

// next.config.js
module.exports = withCss(
  withPurgeCss({
    purgeCssPaths: [
      "pages/**/*",
      "components/**/*",
      "other-components/**/*", // also scan other-components folder
    ],
  })
);
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# purgeCss

You can pass custom options to PurgeCSS(opens new window) by defining purgeCss object in your next.config.js.

// next.config.js
module.exports = withCss(
  withPurgeCss({
    purgeCss: {
      whitelist: () => ["my-custom-class"],
    },
  })
);
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The list of available options are documented in purgecss-webpack-plugin docs(opens new window) .

WARNING

purgeCss.paths will overwrite purgeCssPaths