Neutrino Style Loader Middleware

@neutrinojs/style-loader is Neutrino middleware for loading and importing stylesheets from modules.

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Features

  • Zero upfront configuration necessary to import stylesheets into modules
  • Automatic stylesheet extraction; importing stylesheets into modules creates bundled external stylesheets
  • Pre-configured to support CSS Modules via *.module.css file extensions
  • CSS Hot Module Replacement support
  • Very extensible to customize as needed

Requirements

  • Node.js v6 LTS, v8, v9
  • Yarn v1.2.1+, or npm v5.4+
  • Neutrino v8

Installation

@neutrinojs/style-loader can be installed via the Yarn or npm clients.

Yarn

❯ yarn add @neutrinojs/style-loader

npm

npm install --save @neutrinojs/style-loader

Usage

@neutrinojs/style-loader can be consumed from the Neutrino API, middleware, or presets. Require this package and plug it into Neutrino:

// Using function middleware format
const styles = require('@neutrinojs/style-loader');

// Use with default options
neutrino.use(styles);

// Usage showing default options
neutrino.use(styles, {
  style: {},
  css: {},
  loaders: [],
  test: /\.css$/,
  ruleId: 'style',
  styleUseId: 'style',
  cssUseId: 'css',
  hotUseId: 'hot',
  hot: true,
  modules: true,
  modulesSuffix: '-modules',
  modulesTest: /\.module.css$/,
  extractId: 'extract',
  extract: {
    plugin: {},
    loader: {}
  }
});
// Using object or array middleware format

// Use with default options
module.exports = {
  use: ['@neutrinojs/style-loader']
};

// Usage showing default options
module.exports = {
  use: [
    ['@neutrinojs/style-loader', {
      style: {},
      css: {},
      loaders: [],
      test: /\.css$/,
      ruleId: 'style',
      styleUseId: 'style',
      cssUseId: 'css',
      hotUseId: 'hot',
      hot: true,
      modules: true,
      modulesSuffix: '-modules',
      modulesTest: /\.module.css$/,
      extractId: 'extract',
      extract: {
        plugin: {},
        loader: {}
      }
    }]
  ]
};
  • style: Set options for the style-loader used when loading CSS files.
  • css: Set options for the css-loader used when loading CSS files.
  • loaders: Provide an array of custom loaders used when loading stylesheets
  • test: File extensions which support stylesheets
  • ruleId: The ID of the webpack-chain rule used to identify the stylesheet loaders
  • styleUseId: The ID of the webpack-chain use used to identify the style-loader
  • cssUseId: The ID of the webpack-chain use used to identify the css-loader
  • hotUseId: The ID of the webpack-chain use used to identify the css-hot-loader
  • hot: Enable usage of CSS Hot Module Replacement. Set to false to disable.
  • modules: Enable usage of CSS modules via *.module.css files. Set to false to disable and skip defining these rules.
  • modulesSuffix: A suffix added to ruleId, styleUseId, cssUseId, hotUseId, and extractId to derive names for modules-related rules. For example, the default -modules suffix will generate a rule ID for the CSS modules rules of style-modules, while the normal rule remains as style.
  • modulesTest: File extensions which support CSS Modules stylesheets
  • extractId: The ID of the webpack-chain plugin used to identify the ExtractTextPlugin
  • extract: Options relating to the ExtractTextPlugin instance. Override extract.plugin to override plugin options. Override extract.loader to override the loader options. Set to false to disable stylesheet extraction.

Custom Loaders

You may wish to perform custom loading on your stylesheets by using SASS, LESS, postcss, and more. You can do this by providing an array of custom loaders to the loaders options to this middleware. Each item in the loaders array corresponds to a webpack loader to use, and can be defined as an object or as a string.

Using an object to define loaders is preferred since it allows options to be overridable in the future, and by other consuming middleware. Each loader object can specify 3 properties:

  • loader: A string referencing the path to the loader to use, e.g. sass-loader or require.resolve('less-loader').
  • options: An object specifying any options needed by the loader.
  • useId: A string identified for the loader, used to reference the loader in the future for overrides or customization by other middleware.

Using a string to define loaders will cause @neutrinojs/style-loader to still generate a loader object. The string will be used as the loader property, options will be left blank, and the useId will be derived from cssUseId option above plus the index of this loader within the loaders array.

Important: The useId for string-defined loaders will start at 2, since all loaders are preceded by the included style-loader and css-loader.

module.exports = {
  use: ['@neutrinojs/style-loader', {
    loaders: [
      // Define loaders as objects
      {
        loader: 'sass-loader',
        useId: 'sass',
        options: {
          includePaths: ['absolute/path/a', 'absolute/path/b']
        }
      },
      {
        loader: 'postcss-loader',
        useId: 'postcss',
        options: {
          config: {

            // Where to look for config (postcss.config.js)
            // https://github.com/postcss/postcss-loader#path
            path: neutrino.options.root
          }
        }
      }
    ]
  }]
}
module.exports = {
  use: ['@neutrinojs/style-loader', {
    loaders: [
      // Define loaders as strings
      // This will cause this middleware to generate a
      // loader with a useId of `css-2`.
      'sass-loader'

      // Adding any other loaders will increment the useId
      // to `css-3`, `css-4`, etc.
    ]
  }]
}

Due to the inferred loader names, we highly recommend you stick to using objects to define loaders.

Customization

@neutrinojs/style-loader creates some conventions to make overriding the configuration easier once you are ready to make changes.

Rules

The following is a list of default rules and their identifiers which can be overridden:

Name Description Environments and Commands
style Allows importing CSS stylesheets from modules. Contains two loaders named style and css which use style-loader and css-loader, respectively. all
style-modules Allows importing CSS Modules styles from modules. Contains two loaders named style-modules and css-modules which use style-loader and css-loader, respectively. all

Plugins

The following is a default list of plugins and their identifiers which can be overridden:

Note: Some plugins may be only available in certain environments. To override them, they should be modified conditionally.

Name Description Environments and Commands
extract Extracts CSS from JS bundle into a separate stylesheet file. all
extract-modules Extracts CSS from JS bundle into a separate stylesheet file. all

Contributing

This middleware is part of the neutrino-dev repository, a monorepo containing all resources for developing Neutrino and its core presets and middleware. Follow the contributing guide for details.

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