style-loader-extra v1.0.2

style-loader

Adds CSS to the DOM by injecting a <style> tag

Getting Started

To begin, you'll need to install css-loader:

npm install --save-dev style-loader

It's recommended to combine style-loader with the css-loader

Then add the loader to your webpack config. For example:

style.css

body {
  background: green;
}

component.js

import style from './style.css';

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [{ loader: 'style-loader' }, { loader: 'css-loader' }],
      },
    ],
  },
};

Locals (CSS Modules)

When using local scoped CSS the module exports the generated identifiers (locals):

component.js

import style from './file.css';

style.className === 'z849f98ca812';

Url

It's also possible to add a URL <link href="path/to/file.css" rel="stylesheet"> instead of inlining the CSS {String} with <style></style> tag.

import url from 'file.css';

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [{ loader: 'style-loader/url' }, { loader: 'file-loader' }],
      },
    ],
  },
};

<link rel="stylesheet" href="path/to/file.css" />

Useable

The style-loader injects the styles lazily making them useable on-demand via style.use() / style.unuse()

By convention the Reference Counter API should be bound to .useable.css and the .css should be loaded with basic style-loader usage.(similar to other file types, i.e. .useable.less and .less).

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        exclude: /\.useable\.css$/,
        use: [{ loader: 'style-loader' }, { loader: 'css-loader' }],
      },
      {
        test: /\.useable\.css$/,
        use: [
          {
            loader: 'style-loader/useable',
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

Reference Counter API

component.js

import style from './file.css';

style.use(); // = style.ref();
style.unuse(); // = style.unref();

Styles are not added on import/require(), but instead on call to use/ref. Styles are removed from page if unuse/unref is called exactly as often as use/ref.

⚠️ Behavior is undefined when unuse/unref is called more often than use/ref. Don't do that.

Options

hmr

Enable/disable Hot Module Replacement (HMR), if disabled no HMR Code will be added. This could be used for non local development and production.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          {
            loader: 'style-loader',
            options: {
              hmr: false,
            },
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

base

This setting is primarily used as a workaround for css clashes when using one or more DllPlugin's. base allows you to prevent either the app's css (or DllPlugin2's css) from overwriting DllPlugin1's css by specifying a css module id base which is greater than the range used by DllPlugin1 e.g.:

webpack.dll1.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          {
            loader: 'style-loader',
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

webpack.dll2.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          { loader: 'style-loader', options: { base: 1000 } },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

webpack.app.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          { loader: 'style-loader', options: { base: 2000 } },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

attributes

If defined, style-loader will attach given attributes with their values on <style> / <link> element.

component.js

import style from './file.css';

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          { loader: 'style-loader', options: { attributes: { id: 'id' } } },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

<style id="id"></style>

Url

component.js

import link from './file.css';

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          { loader: 'style-loader/url', options: { attributes: { id: 'id' } } },
          { loader: 'file-loader' },
        ],
      },
    ],
  },
};

insertAt

By default, the style-loader appends <style> elements to the end of the style target, which is the <head> tag of the page unless specified by insertInto. This will cause CSS created by the loader to take priority over CSS already present in the target. To insert style elements at the beginning of the target, set this query parameter to 'top', e.g

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          {
            loader: 'style-loader',
            options: {
              insertAt: 'top',
            },
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

A new <style> element can be inserted before a specific element by passing an object, e.g.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          {
            loader: 'style-loader',
            options: {
              insertAt: {
                before: '#id',
              },
            },
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

insertInto

By default, the style-loader inserts the <style> elements into the <head> tag of the page. If you want the tags to be inserted somewhere else you can specify a CSS selector for that element here. If you target an IFrame make sure you have sufficient access rights, the styles will be injected into the content document head.

You can also pass function to override default behavior and insert styles in your container, e.g

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          {
            loader: 'style-loader',
            options: {
              insertInto: () => document.querySelector('#root'),
            },
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

Using function you can insert the styles into a ShadowRoot, e.g

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          {
            loader: 'style-loader',
            options: {
              insertInto: () => document.querySelector('#root').shadowRoot,
            },
          },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

singleton

If defined, the style-loader will reuse a single <style></style> element, instead of adding/removing individual elements for each required module.

ℹ️ This option is on by default in IE9, which has strict limitations on the number of style tags allowed on a page. You can enable or disable it with the singleton option.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          { loader: 'style-loader', options: { singleton: true } },
          { loader: 'css-loader' },
        ],
      },
    ],
  },
};

sourceMap

Enable/Disable source map loading

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          { loader: 'style-loader', options: { sourceMap: true } },
          { loader: 'css-loader', options: { sourceMap: true } },
        ],
      },
    ],
  },
};

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT