postcss-lightningcss

This PostCSS plugin uses lightningcss to compile and minify your CSS.

lightningcss is more than a minifier as it can replace quite a few PostCSS plugins such as autoprefixer. You can find the complete list of features in the package's documentation and the list of plugins it's able to replace below.

Install

yarn add -D postcss-lightningcss

Usage

const postcss = require("postcss");
const postcssLightningcss = require("postcss-lightningcss");

postcss([postcssLightningcss(/* pluginOptions */)]).process(
  YOUR_CSS /*, processOptions */
);

Options

const postcssLightningcss = require("postcss-lightningcss");

postcssLightningcss({
  // Use a browserslist query that will inform which browsers are supported
  // Will add or remove vendor prefixes that are needed or not anymore
  browsers: ">= .25%",
  // Auto set lightningcssOptions.cssModules, possible values:
  // - auto - enable CSS modules for all files matching `/\.module(s)?\.\w+$/i.test(filename)`
  // - RegExp - enable CSS modules for all files matching `/RegExp/i.test(filename)`
  // - boolean - true enable css modules for all files
  // Will be overwrite by the lightningcssOptions cssModules(boolean) option
  cssModules: /\.module\.css/,
  // Will pass all options to lightningcss
  // Check out their documentation for details:
  // https://www.npmjs.com/package/lightningcss#user-content-documentation
  lightningcssOptions: {
    // Enable minification (default: true)
    minify: true,

    // Enable source maps (default: true)
    sourceMap: true,

    // Compile as cssModules (default: undefined)
    cssModules: false,

    // For which browsers to compile (default: undefined)
    // Can be omitted if you set the `browsers` option
    targets: {
      safari: (13 << 16) | (2 << 8), // represents Safari 13.2.0
    },

    // Individually enable various drafts
    drafts: {
      // Enable css nesting (default: undefined)
      nesting: false,
    },
  },
});

The detailed list of lightningcssOptions can be found here

About source maps

Source maps will pass through lightningcss. But many mappings will be lost in translation; lightningcss creates only a source map for selectors. Mappings for properties cannot be re-created after this transformation.

PostCSS plugins that you can remove if you have `lightningcss`

The rows marked as "Depends on browser config" will convert your CSS only if:

You set the browsers or lightningcssOptions.targets options
one of the target browsers doesn't support the feature

PostCSS Plugin	lightningcss option
`autoprefixer`	Depends on browser config
`postcss-clamp`	Depends on browser config
`postcss-color-hex-alpha`	Depends on browser config
`postcss-color-hsl`	Depends on browser config
`postcss-color-rgb`	Depends on browser config
`postcss-color-function`	Depends on browser config
`postcss-color-rebeccapurple`	Depends on browser config
`postcss-custom-media`	`lightningcssOptions.drafts.customMedia`
`postcss-double-position-gradients`	Depends on browser config
`postcss-hwb-function`	Depends on browser config
`postcss-lab-function`	Depends on browser config
`postcss-logical`	Depends on browser config (1)
`postcss-media-minmax`	Depends on browser config
`postcss-multi-value-display`	Depends on browser config
`postcss-nesting`	`lightningcssOptions.drafts.nesting`
`postcss-normalize-display-values`	Depends on browser config
`postcss-oklab-function`	Depends on browser config
`postcss-overflow-shorthand`	Depends on browser config
`postcss-place`	Depends on browser config
`postcss-progressive-custom-properties`	Depends on browser config (2)

lightningcss doesn't support the logical shorthand keyword as its syntax is likely to change
Progressive custom properties works only if the properties don't contain properties themselves:

lab(29.2345% 39.3825 20.0664) has a proper fallback
oklch(40% 0.234 0.39 / var(--opacity-50)) will not have a fallback

License

MIT

npm