1271 lines
		
	
	
		
			27 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
			
		
		
	
	
			1271 lines
		
	
	
		
			27 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
<div align="center">
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  <a href="https://github.com/webpack/webpack">
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    <img width="200" height="200"
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      src="https://webpack.js.org/assets/icon-square-big.svg">
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  </a>
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  <h1>Style Loader</h1>
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</div>
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[![npm][npm]][npm-url]
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[![node][node]][node-url]
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[![tests][tests]][tests-url]
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[![coverage][cover]][cover-url]
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[![discussion][discussion]][discussion-url]
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[![size][size]][size-url]
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# style-loader
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Inject CSS into the DOM.
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## Getting Started
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To begin, you'll need to install `style-loader`:
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```console
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npm install --save-dev style-loader
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```
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or
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```console
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yarn add -D style-loader
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```
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or
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```console
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pnpm add -D style-loader
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```
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It's recommended to combine `style-loader` with the [`css-loader`](https://github.com/webpack-contrib/css-loader)
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Then add the loader to your `webpack` config. For example:
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**style.css**
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```css
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body {
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  background: green;
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}
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```
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**component.js**
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```js
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import "./style.css";
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```
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**webpack.config.js**
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```js
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module.exports = {
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  module: {
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    rules: [
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      {
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        test: /\.css$/i,
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        use: ["style-loader", "css-loader"],
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      },
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    ],
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  },
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};
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```
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## Security Warning
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This loader is primarily meant for development. The default settings are not safe for production environments. See the [recommended example configuration](#recommend) and the section on [nonces](#nonce) for details.
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## Options
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- [**`injectType`**](#injecttype)
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- [**`attributes`**](#attributes)
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- [**`insert`**](#insert)
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- [**`styleTagTransform`**](#styleTagTransform)
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- [**`base`**](#base)
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- [**`esModule`**](#esmodule)
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### `injectType`
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Type:
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```ts
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type injectType =
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  | "styleTag"
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  | "singletonStyleTag"
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  | "autoStyleTag"
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  | "lazyStyleTag"
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  | "lazySingletonStyleTag"
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  | "lazyAutoStyleTag"
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  | "linkTag";
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```
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Default: `styleTag`
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Allows to setup how styles will be injected into the DOM.
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Possible values:
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#### `styleTag`
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Automatically injects styles into the DOM using multiple `<style></style>`. It is **default** behaviour.
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**component.js**
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```js
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import "./styles.css";
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```
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Example with Locals (CSS Modules):
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**component-with-css-modules.js**
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```js
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import * as styles from "./styles.css";
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const divElement = document.createElement("div");
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divElement.className = styles["my-class"];
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```
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All local variables (class names) are exported as named exports. To achieve this behaviour you also have to setup `modules` option for `css-loader`. For more information consult with `css-loader` [`documentation`](https://github.com/webpack-contrib/css-loader).
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						||
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**webpack.config.js**
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```js
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module.exports = {
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  module: {
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    rules: [
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      {
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        test: /\.css$/i,
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        use: [
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          // The `injectType`  option can be avoided because it is default behaviour
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          { loader: "style-loader", options: { injectType: "styleTag" } },
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          {
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            loader: "css-loader",
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            // Uncomment it if you want to use CSS modules
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            // options: { modules: true }
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          },
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        ],
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      },
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    ],
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  },
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};
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```
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The loader inject styles like:
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```html
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<style>
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  .foo {
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    color: red;
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  }
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</style>
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<style>
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  .bar {
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    color: blue;
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  }
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</style>
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```
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#### `singletonStyleTag`
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Automatically injects styles into the DOM using one `<style></style>`.
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> **Warning**
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>
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> Source maps do not work.
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**component.js**
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```js
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import "./styles.css";
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```
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**component-with-css-modules.js**
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```js
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import * as styles from "./styles.css";
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const divElement = document.createElement("div");
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divElement.className = styles["my-class"];
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						||
```
 | 
						||
 | 
						||
All local variables (class names) are exported as named exports. To achieve this behaviour you also have to setup `modules` option for `css-loader`. For more information consult with `css-loader` [`documentation`](https://github.com/webpack-contrib/css-loader).
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
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module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
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        use: [
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          {
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            loader: "style-loader",
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            options: { injectType: "singletonStyleTag" },
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          },
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          {
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            loader: "css-loader",
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            // Uncomment it if you want to use CSS modules
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            // options: { modules: true }
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          },
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						||
        ],
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						||
      },
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						||
    ],
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						||
  },
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						||
};
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```
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						||
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						||
The loader inject styles like:
 | 
						||
 | 
						||
```html
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						||
<style>
 | 
						||
  .foo {
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						||
    color: red;
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						||
  }
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						||
  .bar {
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						||
    color: blue;
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  }
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</style>
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```
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						||
#### `autoStyleTag`
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						||
Works the same as a [`styleTag`](#styleTag), but if the code is executed in IE6-9, turns on the [`singletonStyleTag`](#singletonStyleTag) mode.
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						||
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#### `lazyStyleTag`
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						||
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Injects styles into the DOM using multiple `<style></style>` on demand.
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						||
We recommend following `.lazy.css` naming convention for lazy styles and the `.css` for basic `style-loader` usage (similar to other file types, i.e. `.lazy.less` and `.less`).
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						||
When you `lazyStyleTag` value the `style-loader` injects the styles lazily making them useable on-demand via `style.use()` / `style.unuse()`.
 | 
						||
 | 
						||
> ⚠️ Behavior is undefined when `unuse` is called more often than `use`. Don't do that.
 | 
						||
 | 
						||
**component.js**
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						||
```js
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import styles from "./styles.lazy.css";
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styles.use();
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						||
// For removing styles you can use
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						||
// styles.unuse();
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						||
```
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						||
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						||
**component-with-css-modules.js**
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```js
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import styles, { "my-class" as myClass } from "./styles.lazy.css";
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						||
styles.use();
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						||
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const divElement = document.createElement("div");
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						||
divElement.className = myClass;
 | 
						||
```
 | 
						||
 | 
						||
All local variables (class names) are exported as named exports. To achieve this behaviour you also have to setup `modules` option for `css-loader`. For more information consult with `css-loader` [`documentation`](https://github.com/webpack-contrib/css-loader).
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
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						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
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						||
        exclude: /\.lazy\.css$/i,
 | 
						||
        use: ["style-loader", "css-loader"],
 | 
						||
      },
 | 
						||
      {
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						||
        test: /\.lazy\.css$/i,
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						||
        use: [
 | 
						||
          { loader: "style-loader", options: { injectType: "lazyStyleTag" } },
 | 
						||
          {
 | 
						||
            loader: "css-loader",
 | 
						||
            // Uncomment it if you want to use CSS modules
 | 
						||
            // options: { modules: true }
 | 
						||
          },
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
The loader inject styles like:
 | 
						||
 | 
						||
```html
 | 
						||
<style>
 | 
						||
  .foo {
 | 
						||
    color: red;
 | 
						||
  }
 | 
						||
</style>
 | 
						||
<style>
 | 
						||
  .bar {
 | 
						||
    color: blue;
 | 
						||
  }
 | 
						||
</style>
 | 
						||
```
 | 
						||
 | 
						||
#### `lazySingletonStyleTag`
 | 
						||
 | 
						||
Injects styles into the DOM using one `<style></style>` on demand.
 | 
						||
We recommend following `.lazy.css` naming convention for lazy styles and the `.css` for basic `style-loader` usage (similar to other file types, i.e. `.lazy.less` and `.less`).
 | 
						||
When you `lazySingletonStyleTag` value the `style-loader` injects the styles lazily making them useable on-demand via `style.use()` / `style.unuse()`.
 | 
						||
 | 
						||
> ⚠️ Source maps do not work.
 | 
						||
 | 
						||
> ⚠️ Behavior is undefined when `unuse` is called more often than `use`. Don't do that.
 | 
						||
 | 
						||
**component.js**
 | 
						||
 | 
						||
```js
 | 
						||
import styles from "./styles.css";
 | 
						||
 | 
						||
styles.use();
 | 
						||
// For removing styles you can use
 | 
						||
// styles.unuse();
 | 
						||
```
 | 
						||
 | 
						||
**component-with-css-modules.js**
 | 
						||
 | 
						||
```js
 | 
						||
import styles, { "my-class" as myClass } from "./styles.lazy.css";
 | 
						||
 | 
						||
styles.use();
 | 
						||
 | 
						||
const divElement = document.createElement("div");
 | 
						||
divElement.className = myClass;
 | 
						||
```
 | 
						||
 | 
						||
All local variables (class names) are exported as named exports. To achieve this behaviour you also have to setup `modules` option for `css-loader`. For more information consult with `css-loader` [`documentation`](https://github.com/webpack-contrib/css-loader).
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        exclude: /\.lazy\.css$/i,
 | 
						||
        use: ["style-loader", "css-loader"],
 | 
						||
      },
 | 
						||
      {
 | 
						||
        test: /\.lazy\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: { injectType: "lazySingletonStyleTag" },
 | 
						||
          },
 | 
						||
          {
 | 
						||
            loader: "css-loader",
 | 
						||
            // Uncomment it if you want to use CSS modules
 | 
						||
            // options: { modules: true }
 | 
						||
          },
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
The loader generate this:
 | 
						||
 | 
						||
```html
 | 
						||
<style>
 | 
						||
  .foo {
 | 
						||
    color: red;
 | 
						||
  }
 | 
						||
  .bar {
 | 
						||
    color: blue;
 | 
						||
  }
 | 
						||
</style>
 | 
						||
```
 | 
						||
 | 
						||
#### `lazyAutoStyleTag`
 | 
						||
 | 
						||
Works the same as a [`lazyStyleTag`](#lazyStyleTag), but if the code is executed in IE6-9, turns on the [`lazySingletonStyleTag`](#lazySingletonStyleTag) mode.
 | 
						||
 | 
						||
#### `linkTag`
 | 
						||
 | 
						||
Injects styles into the DOM using multiple `<link rel="stylesheet" href="path/to/file.css">` .
 | 
						||
 | 
						||
> ℹ️ The loader will dynamically insert the `<link href="path/to/file.css" rel="stylesheet">` tag at runtime via JavaScript. You should use [MiniCssExtractPlugin](https://webpack.js.org/plugins/mini-css-extract-plugin/) if you want to include a static `<link href="path/to/file.css" rel="stylesheet">`.
 | 
						||
 | 
						||
```js
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						||
import "./styles.css";
 | 
						||
import "./other-styles.css";
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.link\.css$/i,
 | 
						||
        use: [
 | 
						||
          { loader: "style-loader", options: { injectType: "linkTag" } },
 | 
						||
          { loader: "file-loader" },
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
The loader generate this:
 | 
						||
 | 
						||
```html
 | 
						||
<link rel="stylesheet" href="path/to/style.css" />
 | 
						||
<link rel="stylesheet" href="path/to/other-styles.css" />
 | 
						||
```
 | 
						||
 | 
						||
### `attributes`
 | 
						||
 | 
						||
Type:
 | 
						||
 | 
						||
```ts
 | 
						||
type attributes = HTMLAttributes;
 | 
						||
```
 | 
						||
 | 
						||
Default: `{}`
 | 
						||
 | 
						||
If defined, the `style-loader` will attach given attributes with their values on `<style>` / `<link>` element.
 | 
						||
 | 
						||
**component.js**
 | 
						||
 | 
						||
```js
 | 
						||
import "./file.css";
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          { loader: "style-loader", options: { attributes: { id: "id" } } },
 | 
						||
          { loader: "css-loader" },
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
```html
 | 
						||
<style id="id"></style>
 | 
						||
```
 | 
						||
 | 
						||
### `insert`
 | 
						||
 | 
						||
Type:
 | 
						||
 | 
						||
```ts
 | 
						||
type insert = string;
 | 
						||
```
 | 
						||
 | 
						||
Default: `head`
 | 
						||
 | 
						||
By default, the `style-loader` appends `<style>`/`<link>` elements to the end of the style target, which is the `<head>` tag of the page unless specified by `insert`.
 | 
						||
This will cause CSS created by the loader to take priority over CSS already present in the target.
 | 
						||
You can use other values if the standard behavior is not suitable for you, but we do not recommend doing this.
 | 
						||
If you target an [iframe](https://developer.mozilla.org/en-US/docs/Web/API/HTMLIFrameElement) make sure you have sufficient access rights, the styles will be injected into the content document head.
 | 
						||
 | 
						||
#### `Selector`
 | 
						||
 | 
						||
Allows to setup custom [query selector](https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelector) where styles inject into the DOM.
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              insert: "body",
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
#### `Absolute path to function`
 | 
						||
 | 
						||
Allows to setup absolute path to custom function that allows to override default behavior and insert styles at any position.
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> Do not forget that this code will be used in the browser and not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc. We recommend using [`babel-loader`](https://webpack.js.org/loaders/babel-loader/) for support latest ECMA features.
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> Do not forget that some DOM methods may not be available in older browsers, we recommended use only [DOM core level 2 properties](https://caniuse.com/#search=DOM%20Core), but it is depends what browsers you want to support
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              insert: require.resolve("./path-to-insert-module"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
A new `<style>`/`<link>` elements will be inserted into at bottom of `body` tag.
 | 
						||
 | 
						||
Examples:
 | 
						||
 | 
						||
Insert styles at top of `head` tag:
 | 
						||
 | 
						||
**insert-function.js**
 | 
						||
 | 
						||
```js
 | 
						||
function insertAtTop(element) {
 | 
						||
  var parent = document.querySelector("head");
 | 
						||
  // eslint-disable-next-line no-underscore-dangle
 | 
						||
  var lastInsertedElement = window._lastElementInsertedByStyleLoader;
 | 
						||
 | 
						||
  if (!lastInsertedElement) {
 | 
						||
    parent.insertBefore(element, parent.firstChild);
 | 
						||
  } else if (lastInsertedElement.nextSibling) {
 | 
						||
    parent.insertBefore(element, lastInsertedElement.nextSibling);
 | 
						||
  } else {
 | 
						||
    parent.appendChild(element);
 | 
						||
  }
 | 
						||
 | 
						||
  // eslint-disable-next-line no-underscore-dangle
 | 
						||
  window._lastElementInsertedByStyleLoader = element;
 | 
						||
}
 | 
						||
 | 
						||
module.exports = insertAtTop;
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              insert: require.resolve("./insert-function"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
You can pass any parameters to `style.use(options)` and this value will be passed to `insert` and `styleTagTransform` functions.
 | 
						||
 | 
						||
**insert-function.js**
 | 
						||
 | 
						||
```js
 | 
						||
function insertIntoTarget(element, options) {
 | 
						||
  var parent = options.target || document.head;
 | 
						||
 | 
						||
  parent.appendChild(element);
 | 
						||
}
 | 
						||
 | 
						||
module.exports = insertIntoTarget;
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              injectType: "lazyStyleTag",
 | 
						||
              // Do not forget that this code will be used in the browser and
 | 
						||
              // not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc,
 | 
						||
              // we recommend use only ECMA 5 features,
 | 
						||
              // but it depends what browsers you want to support
 | 
						||
              insert: require.resolve("./insert-function.js"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
Insert styles to the provided element or to the `head` tag if target isn't provided. Now you can inject styles into Shadow DOM (or any other element).
 | 
						||
 | 
						||
**custom-square.css**
 | 
						||
 | 
						||
```css
 | 
						||
div {
 | 
						||
  width: 50px;
 | 
						||
  height: 50px;
 | 
						||
  background-color: red;
 | 
						||
}
 | 
						||
```
 | 
						||
 | 
						||
**custom-square.js**
 | 
						||
 | 
						||
```js
 | 
						||
import customSquareStyles from "./custom-square.css";
 | 
						||
 | 
						||
class CustomSquare extends HTMLElement {
 | 
						||
  constructor() {
 | 
						||
    super();
 | 
						||
 | 
						||
    this.attachShadow({ mode: "open" });
 | 
						||
 | 
						||
    const divElement = document.createElement("div");
 | 
						||
 | 
						||
    divElement.textContent = "Text content.";
 | 
						||
 | 
						||
    this.shadowRoot.appendChild(divElement);
 | 
						||
 | 
						||
    customSquareStyles.use({ target: this.shadowRoot });
 | 
						||
 | 
						||
    // You can override injected styles
 | 
						||
    const bgPurple = new CSSStyleSheet();
 | 
						||
    const width = this.getAttribute("w");
 | 
						||
    const height = this.getAttribute("h");
 | 
						||
 | 
						||
    bgPurple.replace(`div { width: ${width}px; height: ${height}px; }`);
 | 
						||
 | 
						||
    this.shadowRoot.adoptedStyleSheets = [bgPurple];
 | 
						||
 | 
						||
    // `divElement` will have `100px` width, `100px` height and `red` background color
 | 
						||
  }
 | 
						||
}
 | 
						||
 | 
						||
customElements.define("custom-square", CustomSquare);
 | 
						||
 | 
						||
export default CustomSquare;
 | 
						||
```
 | 
						||
 | 
						||
### `styleTagTransform`
 | 
						||
 | 
						||
Type:
 | 
						||
 | 
						||
```ts
 | 
						||
type styleTagTransform = string;
 | 
						||
```
 | 
						||
 | 
						||
Default: `undefined`
 | 
						||
 | 
						||
#### `string`
 | 
						||
 | 
						||
Allows to setup absolute path to custom function that allows to override default behavior styleTagTransform.
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> Do not forget that this code will be used in the browser and not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc, we recommend use only ECMA 5 features, but it is depends what browsers you want to support
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> Do not forget that some DOM methods may not be available in older browsers, we recommended use only [DOM core level 2 properties](https://caniuse.com/#search=DOM%20Core), but it depends what browsers you want to support
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              injectType: "styleTag",
 | 
						||
              styleTagTransform: require.resolve("style-tag-transform-code"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
### `base`
 | 
						||
 | 
						||
```ts
 | 
						||
type base = number;
 | 
						||
```
 | 
						||
 | 
						||
This setting is primarily used as a workaround for [css clashes](https://github.com/webpack-contrib/style-loader/issues/163) when using one or more [DllPlugin](https://robertknight.me.uk/posts/webpack-dll-plugins/)'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**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: ["style-loader", "css-loader"],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
**webpack.dll2.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          { loader: "style-loader", options: { base: 1000 } },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
**webpack.app.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          { loader: "style-loader", options: { base: 2000 } },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
### `esModule`
 | 
						||
 | 
						||
Type:
 | 
						||
 | 
						||
```ts
 | 
						||
type esModule = boolean;
 | 
						||
```
 | 
						||
 | 
						||
Default: `true`
 | 
						||
 | 
						||
By default, `style-loader` generates JS modules that use the ES modules syntax.
 | 
						||
There are some cases in which using ES modules is beneficial, like in the case of [module concatenation](https://webpack.js.org/plugins/module-concatenation-plugin/) and [tree shaking](https://webpack.js.org/guides/tree-shaking/).
 | 
						||
 | 
						||
You can enable a CommonJS modules syntax using:
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        loader: "style-loader",
 | 
						||
        options: {
 | 
						||
          esModule: false,
 | 
						||
        },
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
## Examples
 | 
						||
 | 
						||
### Recommend
 | 
						||
 | 
						||
For `production` builds it's recommended to extract the CSS from your bundle being able to use parallel loading of CSS/JS resources later on.
 | 
						||
This can be achieved by using the [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin), because it creates separate css files.
 | 
						||
For `development` mode (including `webpack-dev-server`) you can use `style-loader`, because it injects CSS into the DOM using multiple `<style></style>` and works faster.
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> Do not use together `style-loader` and `mini-css-extract-plugin`.
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
 | 
						||
const devMode = process.env.NODE_ENV !== "production";
 | 
						||
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.(sa|sc|c)ss$/,
 | 
						||
        use: [
 | 
						||
          devMode ? "style-loader" : MiniCssExtractPlugin.loader,
 | 
						||
          "css-loader",
 | 
						||
          "postcss-loader",
 | 
						||
          "sass-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
  plugins: [].concat(devMode ? [] : [new MiniCssExtractPlugin()]),
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
### Named export for CSS Modules
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> It is not allowed to use JavaScript reserved words in css class names.
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> Options `esModule` and `modules.namedExport` in `css-loader` should be enabled (by default for `css-loader@7` it is true).
 | 
						||
 | 
						||
**styles.css**
 | 
						||
 | 
						||
```css
 | 
						||
.fooBaz {
 | 
						||
  color: red;
 | 
						||
}
 | 
						||
.bar {
 | 
						||
  color: blue;
 | 
						||
}
 | 
						||
.my-class {
 | 
						||
  color: green;
 | 
						||
}
 | 
						||
```
 | 
						||
 | 
						||
**index.js**
 | 
						||
 | 
						||
```js
 | 
						||
import { fooBaz, bar, "my-class" as myClass } from "./styles.css";
 | 
						||
 | 
						||
console.log(fooBaz, bar, myClass);
 | 
						||
```
 | 
						||
 | 
						||
Or:
 | 
						||
 | 
						||
**index.js**
 | 
						||
 | 
						||
```js
 | 
						||
import * as styles from "./styles.css";
 | 
						||
 | 
						||
console.log(styles.fooBaz, styles.bar, styles["my-class"]);
 | 
						||
```
 | 
						||
 | 
						||
You can enable a ES module named export using:
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
          },
 | 
						||
          {
 | 
						||
            loader: "css-loader",
 | 
						||
            options: {
 | 
						||
              modules: {
 | 
						||
                namedExport: true,
 | 
						||
              },
 | 
						||
            },
 | 
						||
          },
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
### Source maps
 | 
						||
 | 
						||
The loader automatically inject source maps when previous loader emit them.
 | 
						||
Therefore, to generate source maps, set the `sourceMap` option to `true` for the previous loader.
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          "style-loader",
 | 
						||
          { loader: "css-loader", options: { sourceMap: true } },
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
### Nonce
 | 
						||
 | 
						||
If you are using a [Content Security Policy](https://www.w3.org/TR/CSP3/) (CSP), the injected code will usually be blocked. A workaround is to use a nonce. Note, however, that using a nonce significantly reduces the protection provided by the CSP. You can read more about the security impact in [the specification](https://www.w3.org/TR/CSP3/#security-considerations). The better solution is not to use this loader in production.
 | 
						||
 | 
						||
There are two ways to work with `nonce`:
 | 
						||
 | 
						||
- using the `attributes` option
 | 
						||
- using the `__webpack_nonce__` variable
 | 
						||
 | 
						||
> **Warning**
 | 
						||
>
 | 
						||
> the `attributes` option takes precedence over the `__webpack_nonce__` variable
 | 
						||
 | 
						||
#### `attributes`
 | 
						||
 | 
						||
**component.js**
 | 
						||
 | 
						||
```js
 | 
						||
import "./style.css";
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              attributes: {
 | 
						||
                nonce: "12345678",
 | 
						||
              },
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
The loader generate:
 | 
						||
 | 
						||
```html
 | 
						||
<style nonce="12345678">
 | 
						||
  .foo {
 | 
						||
    color: red;
 | 
						||
  }
 | 
						||
</style>
 | 
						||
```
 | 
						||
 | 
						||
#### `__webpack_nonce__`
 | 
						||
 | 
						||
**create-nonce.js**
 | 
						||
 | 
						||
```js
 | 
						||
__webpack_nonce__ = "12345678";
 | 
						||
```
 | 
						||
 | 
						||
**component.js**
 | 
						||
 | 
						||
```js
 | 
						||
import "./create-nonce.js";
 | 
						||
import "./style.css";
 | 
						||
```
 | 
						||
 | 
						||
Alternative example for `require`:
 | 
						||
 | 
						||
**component.js**
 | 
						||
 | 
						||
```js
 | 
						||
__webpack_nonce__ = "12345678";
 | 
						||
 | 
						||
require("./style.css");
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: ["style-loader", "css-loader"],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
The loader generate:
 | 
						||
 | 
						||
```html
 | 
						||
<style nonce="12345678">
 | 
						||
  .foo {
 | 
						||
    color: red;
 | 
						||
  }
 | 
						||
</style>
 | 
						||
```
 | 
						||
 | 
						||
#### Insert styles at top
 | 
						||
 | 
						||
Insert styles at top of `head` tag.
 | 
						||
 | 
						||
**insert-function.js**
 | 
						||
 | 
						||
```js
 | 
						||
function insertAtTop(element) {
 | 
						||
  var parent = document.querySelector("head");
 | 
						||
  var lastInsertedElement = window._lastElementInsertedByStyleLoader;
 | 
						||
 | 
						||
  if (!lastInsertedElement) {
 | 
						||
    parent.insertBefore(element, parent.firstChild);
 | 
						||
  } else if (lastInsertedElement.nextSibling) {
 | 
						||
    parent.insertBefore(element, lastInsertedElement.nextSibling);
 | 
						||
  } else {
 | 
						||
    parent.appendChild(element);
 | 
						||
  }
 | 
						||
 | 
						||
  window._lastElementInsertedByStyleLoader = element;
 | 
						||
}
 | 
						||
 | 
						||
module.exports = insertAtTop;
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              insert: require.resolve("./insert-function.js"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
#### Insert styles before target element
 | 
						||
 | 
						||
Inserts styles before `#id` element.
 | 
						||
 | 
						||
**insert-function.js**
 | 
						||
 | 
						||
```js
 | 
						||
function insertBeforeAt(element) {
 | 
						||
  const parent = document.querySelector("head");
 | 
						||
  const target = document.querySelector("#id");
 | 
						||
 | 
						||
  const lastInsertedElement = window._lastElementInsertedByStyleLoader;
 | 
						||
 | 
						||
  if (!lastInsertedElement) {
 | 
						||
    parent.insertBefore(element, target);
 | 
						||
  } else if (lastInsertedElement.nextSibling) {
 | 
						||
    parent.insertBefore(element, lastInsertedElement.nextSibling);
 | 
						||
  } else {
 | 
						||
    parent.appendChild(element);
 | 
						||
  }
 | 
						||
 | 
						||
  window._lastElementInsertedByStyleLoader = element;
 | 
						||
}
 | 
						||
 | 
						||
module.exports = insertBeforeAt;
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              insert: require.resolve("./insert-function.js"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
#### Custom Elements (Shadow DOM)
 | 
						||
 | 
						||
You can define custom target for your styles for the `lazyStyleTag` type.
 | 
						||
 | 
						||
**insert-function.js**
 | 
						||
 | 
						||
```js
 | 
						||
function insertIntoTarget(element, options) {
 | 
						||
  var parent = options.target || document.head;
 | 
						||
 | 
						||
  parent.appendChild(element);
 | 
						||
}
 | 
						||
 | 
						||
module.exports = insertIntoTarget;
 | 
						||
```
 | 
						||
 | 
						||
**webpack.config.js**
 | 
						||
 | 
						||
```js
 | 
						||
module.exports = {
 | 
						||
  module: {
 | 
						||
    rules: [
 | 
						||
      {
 | 
						||
        test: /\.css$/i,
 | 
						||
        use: [
 | 
						||
          {
 | 
						||
            loader: "style-loader",
 | 
						||
            options: {
 | 
						||
              injectType: "lazyStyleTag",
 | 
						||
              // Do not forget that this code will be used in the browser and
 | 
						||
              // not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc,
 | 
						||
              // we recommend use only ECMA 5 features,
 | 
						||
              // but it is depends what browsers you want to support
 | 
						||
              insert: require.resolve("./insert-function.js"),
 | 
						||
            },
 | 
						||
          },
 | 
						||
          "css-loader",
 | 
						||
        ],
 | 
						||
      },
 | 
						||
    ],
 | 
						||
  },
 | 
						||
};
 | 
						||
```
 | 
						||
 | 
						||
Insert styles to the provided element or to the `head` tag if target isn't provided.
 | 
						||
 | 
						||
**custom-square.css**
 | 
						||
 | 
						||
```css
 | 
						||
div {
 | 
						||
  width: 50px;
 | 
						||
  height: 50px;
 | 
						||
  background-color: red;
 | 
						||
}
 | 
						||
```
 | 
						||
 | 
						||
**custom-square.js**
 | 
						||
 | 
						||
```js
 | 
						||
import customSquareStyles from "./custom-square.css";
 | 
						||
 | 
						||
class CustomSquare extends HTMLElement {
 | 
						||
  constructor() {
 | 
						||
    super();
 | 
						||
 | 
						||
    this.attachShadow({ mode: "open" });
 | 
						||
 | 
						||
    const divElement = document.createElement("div");
 | 
						||
 | 
						||
    divElement.textContent = "Text content.";
 | 
						||
 | 
						||
    this.shadowRoot.appendChild(divElement);
 | 
						||
 | 
						||
    customSquareStyles.use({ target: this.shadowRoot });
 | 
						||
 | 
						||
    // You can override injected styles
 | 
						||
    const bgPurple = new CSSStyleSheet();
 | 
						||
    const width = this.getAttribute("w");
 | 
						||
    const height = this.getAttribute("h");
 | 
						||
 | 
						||
    bgPurple.replace(`div { width: ${width}px; height: ${height}px; }`);
 | 
						||
 | 
						||
    this.shadowRoot.adoptedStyleSheets = [bgPurple];
 | 
						||
 | 
						||
    // `divElement` will have `100px` width, `100px` height and `red` background color
 | 
						||
  }
 | 
						||
}
 | 
						||
 | 
						||
customElements.define("custom-square", CustomSquare);
 | 
						||
 | 
						||
export default CustomSquare;
 | 
						||
```
 | 
						||
 | 
						||
## Contributing
 | 
						||
 | 
						||
Please take a moment to read our contributing guidelines if you haven't yet done so.
 | 
						||
 | 
						||
[CONTRIBUTING](./.github/CONTRIBUTING.md)
 | 
						||
 | 
						||
## License
 | 
						||
 | 
						||
[MIT](./LICENSE)
 | 
						||
 | 
						||
[npm]: https://img.shields.io/npm/v/style-loader.svg
 | 
						||
[npm-url]: https://npmjs.com/package/style-loader
 | 
						||
[node]: https://img.shields.io/node/v/style-loader.svg
 | 
						||
[node-url]: https://nodejs.org
 | 
						||
[tests]: https://github.com/webpack-contrib/style-loader/workflows/style-loader/badge.svg
 | 
						||
[tests-url]: https://github.com/webpack-contrib/style-loader/actions
 | 
						||
[cover]: https://codecov.io/gh/webpack-contrib/style-loader/branch/master/graph/badge.svg
 | 
						||
[cover-url]: https://codecov.io/gh/webpack-contrib/style-loader
 | 
						||
[discussion]: https://img.shields.io/github/discussions/webpack/webpack
 | 
						||
[discussion-url]: https://github.com/webpack/webpack/discussions
 | 
						||
[size]: https://packagephobia.now.sh/badge?p=style-loader
 | 
						||
[size-url]: https://packagephobia.now.sh/result?p=style-loader
 |