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 10+
  • Yarn v1.2.1+, or npm v5.4+
  • Neutrino 9
  • webpack 4

Installation

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

Yarn

❯ yarn add --dev @neutrinojs/style-loader

npm

❯ npm install --save-dev @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:

const styles = require('@neutrinojs/style-loader');

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

// Usage showing default options
neutrino.use(
  styles({
    style: {},
    css: {
      importLoaders: opts.loaders ? opts.loaders.length : 0,
    },
    loaders: [],
    test: /\.css$/,
    ruleId: 'style',
    modules: true,
    modulesTest: /\.module.css$/,
    extract: {
      enabled: process.env.NODE_ENV === 'production',
      loader: {},
      plugin: {
        filename:
          process.env.NODE_ENV === 'production'
            ? 'assets/[name].[contenthash:8].css'
            : 'assets/[name].css',
      },
    },
  }),
);
// Using in .neutrinorc.js
const styles = require('@neutrinojs/style-loader');

// Use with default options
module.exports = {
  use: [styles()],
};

// Usage with options
module.exports = {
  use: [
    styles({
      modules: false,
    }),
  ],
};
  • 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
  • modules: Enable usage of CSS modules via *.module.css files. Set to false to disable and skip defining these rules.
  • modulesTest: File extensions which support CSS Modules stylesheets
  • 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 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.

const styles = require('@neutrinojs/style-loader');

module.exports = {
  use: [
    styles({
      // Override the default file extension of `.css` if needed
      test: /\.(css|sass|scss)$/,
      modulesTest: /\.module\.(css|sass|scss)$/,
      loaders: [
        // Define loaders as objects. Note: loaders must be specified in reverse order.
        // ie: for the loaders below the actual execution order would be:
        // input file -> sass-loader -> postcss-loader -> css-loader -> style-loader/mini-css-extract-plugin
        {
          loader: 'postcss-loader',
          options: {
            plugins: [require('autoprefixer')],
          },
        },
        {
          loader: 'sass-loader',
          useId: 'sass',
          options: {
            includePaths: ['absolute/path/a', 'absolute/path/b'],
          },
        },
      ],
    }),
  ],
};
const styles = require('@neutrinojs/style-loader');

module.exports = {
  use: [
    styles({
      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.

Loader Configuration

You can configure loaders directly by passing options. For PostCSS, if you want to use an external config file, you need to pass options.config:

// .neutrinorc.js
const styles = require('@neutrinojs/style-loader');

module.exports = {
  use: [
    styles({
      loaders: [
        {
          loader: 'postcss-loader',
          useId: 'postcss',
          options: {
            config: {
              // Where to look for config (postcss.config.js)
              // https://github.com/postcss/postcss-loader#path
              // See "Loader Configuration" below
              path: neutrino.options.root,
            },
          },
        },
      ],
    }),
  ],
};
// .postcssrc.js
// Example: load tailwindcss plugin
module.exports = {
  plugins: {
    tailwindcss: {},
  },
};

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/oneOfs and their identifiers which can be overridden:

Name Description NODE_ENV
style A parent rule containing oneOf rules for importing stylesheets. all
style.normal Allows importing CSS stylesheets from modules. By default contains two loaders named extract and css which use MiniCssExtractPlugin.loader and css-loader, respectively. If options.extract is false, then the extract loader is replaced by style, which uses style-loader. all
style.modules Allows importing CSS Modules styles from modules. By default contains two loaders named extract and css which use MiniCssExtractPlugin.loader and css-loader, respectively. If options.extract is false, then the extract loader is replaced by style, which uses style-loader. 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 NODE_ENV
extract Extracts CSS from JS bundle into a separate stylesheet file. 'production'

Contributing

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