| 1 | [![npm][npm]][npm-url]
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| 2 | [![node][node]][node-url]
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| 3 | [![deps][deps]][deps-url]
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| 4 | [![chat][chat]][chat-url]
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| 5 |
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| 6 | <div align="center">
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| 7 | <a href="https://github.com/webpack/webpack">
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| 8 | <img width="200" height="200"
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| 9 | src="https://webpack.js.org/assets/icon-square-big.svg">
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| 10 | </a>
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| 11 | <h1>Style Loader</h1>
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| 12 | <p>Adds CSS to the DOM by injecting a <code><style></code> tag</p>
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| 13 | </div>
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| 14 |
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| 15 | <h2 align="center">Install</h2>
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| 16 |
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| 17 | ```bash
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| 18 | npm install style-loader --save-dev
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| 19 | ```
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| 20 |
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| 21 | <h2 align="center"><a href="https://webpack.js.org/concepts/loaders">Usage</a></h2>
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| 22 |
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| 23 | It's recommended to combine `style-loader` with the [`css-loader`](https://github.com/webpack/css-loader)
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| 24 |
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| 25 | **component.js**
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| 26 | ```js
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| 27 | import style from './file.css'
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| 28 | ```
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| 29 |
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| 30 | **webpack.config.js**
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| 31 | ```js
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| 32 | {
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| 33 | module: {
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| 34 | rules: [
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| 35 | {
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| 36 | test: /\.css$/,
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| 37 | use: [
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| 38 | { loader: "style-loader" },
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| 39 | { loader: "css-loader" }
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| 40 | ]
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| 41 | }
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| 42 | ]
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| 43 | }
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| 44 | }
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| 45 | ```
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| 46 |
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| 47 | #### `Locals (CSS Modules)`
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| 48 |
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| 49 | When using [local scoped CSS](https://github.com/webpack/css-loader#css-scope) the module exports the generated identifiers (locals).
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| 50 |
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| 51 | **component.js**
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| 52 | ```js
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| 53 | import style from './file.css'
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| 54 |
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| 55 | style.className === "z849f98ca812"
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| 56 | ```
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| 57 |
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| 58 | ### `Url`
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| 59 |
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| 60 | 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.
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| 61 |
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| 62 | ```js
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| 63 | import url from 'file.css'
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| 64 | ```
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| 65 |
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| 66 | **webpack.config.js**
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| 67 | ```js
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| 68 | {
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| 69 | module: {
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| 70 | rules: [
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| 71 | {
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| 72 | test: /\.css$/,
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| 73 | use: [
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| 74 | { loader: "style-loader/url" },
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| 75 | { loader: "file-loader" }
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| 76 | ]
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| 77 | }
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| 78 | ]
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| 79 | }
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| 80 | }
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| 81 | ```
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| 82 |
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| 83 | ```html
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| 84 | <link rel="stylesheet" href="path/to/file.css">
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| 85 | ```
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| 86 |
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| 87 | > :information_source: Source maps and assets referenced with `url`: when style loader is used with `{ options: { sourceMap: true } }` option, the CSS modules will be generated as `Blob`s, so relative paths don't work (they would be relative to `chrome:blob` or `chrome:devtools`). In order for assets to maintain correct paths setting `output.publicPath` property of webpack configuration must be set, so that absolute paths are generated. Alternatively you can enable the `convertToAbsoluteUrls` option mentioned above.
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| 88 |
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| 89 | ### `Useable`
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| 90 |
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| 91 | 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`).
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| 92 |
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| 93 | **webpack.config.js**
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| 94 | ```js
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| 95 | {
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| 96 | module: {
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| 97 | rules: [
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| 98 | {
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| 99 | test: /\.css$/,
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| 100 | use: [
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| 101 | { loader: "style-loader" },
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| 102 | { loader: "css-loader" },
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| 103 | ],
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| 104 | },
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| 105 | {
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| 106 | test: /\.useable\.css$/,
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| 107 | use: [
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| 108 | {
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| 109 | loader: "style-loader/useable"
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| 110 | },
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| 111 | { loader: "css-loader" },
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| 112 | ],
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| 113 | },
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| 114 | ],
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| 115 | },
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| 116 | }
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| 117 | ```
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| 118 |
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| 119 | #### `Reference Counter API`
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| 120 |
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| 121 | **component.js**
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| 122 | ```js
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| 123 | import style from './file.css'
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| 124 |
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| 125 | style.use(); // = style.ref();
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| 126 | style.unuse(); // = style.unref();
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| 127 | ```
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| 128 |
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| 129 | 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`.
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| 130 |
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| 131 | :warning: Behavior is undefined when `unuse`/`unref` is called more often than `use`/`ref`. Don't do that.
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| 132 |
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| 133 | <h2 align="center">Options</h2>
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| 134 |
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| 135 | |Name|Type|Default|Description|
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| 136 | |:--:|:--:|:-----:|:----------|
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| 137 | |**`hmr`**|`{Boolean}`|`true`|Enable/disable Hot Module Replacement (HMR), if disabled no HMR Code will be added (good for non local development/production)|
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| 138 | |**`base`** |`{Number}`|`true`|Set module ID base (DLLPlugin)|
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| 139 | |**`attrs`**|`{Object}`|`{}`|Add custom attrs to `<style></style>`|
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| 140 | |**`transform`** |`{Function}`|`false`|Transform/Conditionally load CSS by passing a transform/condition function|
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| 141 | |**`insertAt`**|`{String\|Object}`|`bottom`|Inserts `<style></style>` at the given position|
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| 142 | |**`insertInto`**|`{String\|Function}`|`<head>`|Inserts `<style></style>` into the given position|
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| 143 | |**`singleton`**|`{Boolean}`|`undefined`|Reuses a single `<style></style>` element, instead of adding/removing individual elements for each required module.|
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| 144 | |**`sourceMap`**|`{Boolean}`|`false`|Enable/Disable Sourcemaps|
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| 145 | |**`convertToAbsoluteUrls`**|`{Boolean}`|`false`|Converts relative URLs to absolute urls, when source maps are enabled|
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| 146 |
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| 147 | ### `hmr`
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| 148 |
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| 149 | Enable/disable Hot Module Replacement (HMR), if disabled no HMR Code will be added.
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| 150 | This could be used for non local development and production.
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| 151 |
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| 152 | **webpack.config.js**
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| 153 | ```js
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| 154 | {
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| 155 | loader: 'style-loader',
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| 156 | options: {
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| 157 | hmr: false
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| 158 | }
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| 159 | }
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| 160 | ```
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| 161 |
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| 162 | ### `base`
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| 163 |
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| 164 | 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.github.io/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.:
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| 165 |
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| 166 | **webpack.dll1.config.js**
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| 167 | ```js
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| 168 | {
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| 169 | test: /\.css$/,
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| 170 | use: [
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| 171 | 'style-loader',
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| 172 | 'css-loader'
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| 173 | ]
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| 174 | }
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| 175 | ```
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| 176 |
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| 177 | **webpack.dll2.config.js**
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| 178 | ```js
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| 179 | {
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| 180 | test: /\.css$/,
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| 181 | use: [
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| 182 | { loader: 'style-loader', options: { base: 1000 } },
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| 183 | 'css-loader'
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| 184 | ]
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| 185 | }
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| 186 | ```
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| 187 |
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| 188 | **webpack.app.config.js**
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| 189 | ```
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| 190 | {
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| 191 | test: /\.css$/,
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| 192 | use: [
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| 193 | { loader: 'style-loader', options: { base: 2000 } },
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| 194 | 'css-loader'
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| 195 | ]
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| 196 | }
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| 197 | ```
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| 198 |
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| 199 | ### `attrs`
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| 200 |
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| 201 | If defined, style-loader will attach given attributes with their values on `<style>` / `<link>` element.
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| 202 |
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| 203 | **component.js**
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| 204 | ```js
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| 205 | import style from './file.css'
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| 206 | ```
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| 207 |
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| 208 | **webpack.config.js**
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| 209 | ```js
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| 210 | {
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| 211 | test: /\.css$/,
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| 212 | use: [
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| 213 | { loader: 'style-loader', options: { attrs: { id: 'id' } } }
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| 214 | { loader: 'css-loader' }
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| 215 | ]
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| 216 | }
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| 217 | ```
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| 218 |
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| 219 | ```html
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| 220 | <style id="id"></style>
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| 221 | ```
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| 222 |
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| 223 | #### `Url`
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| 224 |
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| 225 | **component.js**
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| 226 | ```js
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| 227 | import link from './file.css'
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| 228 | ```
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| 229 |
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| 230 | **webpack.config.js**
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| 231 | ```js
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| 232 | {
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| 233 | test: /\.css$/,
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| 234 | use: [
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| 235 | { loader: 'style-loader/url', options: { attrs: { id: 'id' } } }
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| 236 | { loader: 'file-loader' }
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| 237 | ]
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| 238 | }
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| 239 | ```
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| 240 |
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| 241 | ### `transform`
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| 242 |
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| 243 | A `transform` is a function that can modify the css just before it is loaded into the page by the style-loader.
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| 244 | This function will be called on the css that is about to be loaded and the return value of the function will be loaded into the page instead of the original css.
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| 245 | If the return value of the `transform` function is falsy, the css will not be loaded into the page at all.
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| 246 |
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| 247 | **webpack.config.js**
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| 248 | ```js
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| 249 | {
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| 250 | loader: 'style-loader',
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| 251 | options: {
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| 252 | transform: 'path/to/transform.js'
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| 253 | }
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| 254 | }
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| 255 | ```
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| 256 |
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| 257 | **transform.js**
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| 258 | ```js
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| 259 | module.exports = function (css) {
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| 260 | // Here we can change the original css
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| 261 | const transformed = css.replace('.classNameA', '.classNameB')
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| 262 |
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| 263 | return transformed
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| 264 | }
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| 265 | ```
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| 266 |
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| 267 | #### `Conditional`
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| 268 |
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| 269 | **webpack.config.js**
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| 270 | ```js
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| 271 | {
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| 272 | loader: 'style-loader',
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| 273 | options: {
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| 274 | transform: 'path/to/conditional.js'
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| 275 | }
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| 276 | }
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| 277 | ```
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| 278 |
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| 279 | **conditional.js**
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| 280 | ```js
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| 281 | module.exports = function (css) {
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| 282 | // If the condition is matched load [and transform] the CSS
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| 283 | if (css.includes('something I want to check')) {
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| 284 | return css;
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| 285 | }
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| 286 | // If a falsy value is returned, the CSS won't be loaded
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| 287 | return false
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| 288 | }
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| 289 | ```
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| 290 |
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| 291 | ### `insertAt`
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| 292 |
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| 293 | 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
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| 294 |
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| 295 | **webpack.config.js**
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| 296 | ```js
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| 297 | {
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| 298 | loader: 'style-loader',
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| 299 | options: {
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| 300 | insertAt: 'top'
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| 301 | }
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| 302 | }
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| 303 | ```
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| 304 |
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| 305 | A new `<style>` element can be inserted before a specific element by passing an object, e.g.
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| 306 |
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| 307 | **webpack.config.js**
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| 308 | ```js
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| 309 | {
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| 310 | loader: 'style-loader',
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| 311 | options: {
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| 312 | insertAt: {
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| 313 | before: '#id'
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| 314 | }
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| 315 | }
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| 316 | }
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| 317 | ```
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| 318 |
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| 319 | ### `insertInto`
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| 320 | 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](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.
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| 321 |
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| 322 | You can also pass function to override default behavior and insert styles in your container, e.g
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| 323 |
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| 324 | **webpack.config.js**
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| 325 | ```js
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| 326 | {
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| 327 | loader: 'style-loader',
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| 328 | options: {
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| 329 | insertInto: () => document.querySelector("#root"),
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| 330 | }
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| 331 | }
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| 332 | ```
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| 333 |
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| 334 | Using function you can insert the styles into a [ShadowRoot](https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot), e.g
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| 335 |
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| 336 | **webpack.config.js**
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| 337 | ```js
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| 338 | {
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| 339 | loader: 'style-loader',
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| 340 | options: {
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| 341 | insertInto: () => document.querySelector("#root").shadowRoot,
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| 342 | }
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| 343 | }
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| 344 | ```
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| 345 |
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| 346 | ### `singleton`
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| 347 |
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| 348 | If defined, the style-loader will reuse a single `<style></style>` element, instead of adding/removing individual elements for each required module.
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| 349 |
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| 350 | > 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.
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| 351 |
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| 352 | **webpack.config.js**
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| 353 | ```js
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| 354 | {
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| 355 | loader: 'style-loader',
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| 356 | options: {
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| 357 | singleton: true
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| 358 | }
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| 359 | }
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| 360 | ```
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| 361 |
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| 362 | ### `sourceMap`
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| 363 |
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| 364 | Enable/Disable source map loading
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| 365 |
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| 366 | **webpack.config.js**
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| 367 | ```js
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| 368 | {
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| 369 | loader: 'style-loader',
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| 370 | options: {
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| 371 | sourceMap: true
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| 372 | }
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| 373 | }
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| 374 | ```
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| 375 |
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| 376 | ### `convertToAbsoluteUrls`
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| 377 |
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| 378 | If convertToAbsoluteUrls and sourceMaps are both enabled, relative urls will be converted to absolute urls right before the css is injected into the page. This resolves [an issue](https://github.com/webpack/style-loader/pull/96) where relative resources fail to load when source maps are enabled. You can enable it with the convertToAbsoluteUrls option.
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| 379 |
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| 380 | **webpack.config.js**
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| 381 | ```js
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| 382 | {
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| 383 | loader: 'style-loader',
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| 384 | options: {
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| 385 | sourceMap: true,
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| 386 | convertToAbsoluteUrls: true
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| 387 | }
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| 388 | }
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| 389 | ```
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| 390 |
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| 391 | <h2 align="center">Maintainers</h2>
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| 392 |
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| 393 | <table>
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| 394 | <tbody>
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| 395 | <tr>
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| 396 | <td align="center">
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| 397 | <a href="https://github.com/bebraw">
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| 398 | <img width="150" height="150" src="https://github.com/bebraw.png?v=3&s=150">
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| 399 | </br>
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| 400 | Juho Vepsäläinen
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| 401 | </a>
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| 402 | </td>
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| 403 | <td align="center">
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| 404 | <a href="https://github.com/d3viant0ne">
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| 405 | <img width="150" height="150" src="https://github.com/d3viant0ne.png?v=3&s=150">
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| 406 | </br>
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| 407 | Joshua Wiens
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| 408 | </a>
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| 409 | </td>
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| 410 | <td align="center">
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| 411 | <a href="https://github.com/sapegin">
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| 412 | <img width="150" height="150" src="https://github.com/sapegin.png?v=3&s=150">
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| 413 | </br>
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| 414 | Artem Sapegin
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| 415 | </a>
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| 416 | </td>
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| 417 | <td align="center">
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| 418 | <a href="https://github.com/michael-ciniawsky">
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| 419 | <img width="150" height="150" src="https://github.com/michael-ciniawsky.png?v=3&s=150">
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| 420 | </br>
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| 421 | Michael Ciniawsky
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| 422 | </a>
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| 423 | </td>
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| 424 | <td align="center">
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| 425 | <a href="https://github.com/evilebottnawi">
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| 426 | <img width="150" height="150" src="https://github.com/evilebottnawi.png?v=3&s=150">
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| 427 | </br>
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| 428 | Alexander Krasnoyarov
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| 429 | </a>
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| 430 | </td>
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| 431 | </tr>
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| 432 | <tr>
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| 433 | <td align="center">
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| 434 | <a href="https://github.com/sokra">
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| 435 | <img width="150" height="150" src="https://github.com/sokra.png?v=3&s=150">
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| 436 | </br>
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| 437 | Tobias Koppers
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| 438 | </a>
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| 439 | </td>
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| 440 | <td align="center">
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| 441 | <a href="https://github.com/SpaceK33z">
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| 442 | <img width="150" height="150" src="https://github.com/SpaceK33z.png?v=3&s=150">
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| 443 | </br>
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| 444 | Kees Kluskens
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| 445 | </a>
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| 446 | </td>
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| 447 | <tr>
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| 448 | <tbody>
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| 449 | </table>
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| 450 |
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| 451 |
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| 452 | [npm]: https://img.shields.io/npm/v/style-loader.svg
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| 453 | [npm-url]: https://npmjs.com/package/style-loader
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| 454 |
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| 455 | [node]: https://img.shields.io/node/v/style-loader.svg
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| 456 | [node-url]: https://nodejs.org
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| 457 |
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| 458 | [deps]: https://david-dm.org/webpack/style-loader.svg
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| 459 | [deps-url]: https://david-dm.org/webpack/file-loader
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| 460 |
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| 461 | [chat]: https://badges.gitter.im/webpack/webpack.svg
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| 462 | [chat-url]: https://gitter.im/webpack/webpack
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