1 | <div align="center">
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2 | <a href="https://github.com/webpack/webpack">
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3 | <img width="200" height="200"
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4 | src="https://webpack.js.org/assets/icon-square-big.svg">
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5 | </a>
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6 | <h1>Style Loader</h1>
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7 | </div>
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8 |
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9 | [![npm][npm]][npm-url]
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10 | [![node][node]][node-url]
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11 | [![tests][tests]][tests-url]
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12 | [![coverage][cover]][cover-url]
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13 | [![discussion][discussion]][discussion-url]
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14 | [![size][size]][size-url]
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15 |
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16 | # style-loader
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17 |
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18 | Inject CSS into the DOM.
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19 |
|
20 | ## Getting Started
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21 |
|
22 | To begin, you'll need to install `style-loader`:
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23 |
|
24 | ```console
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25 | npm install --save-dev style-loader
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26 | ```
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27 |
|
28 | or
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29 |
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30 | ```console
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31 | yarn add -D style-loader
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32 | ```
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33 |
|
34 | or
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35 |
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36 | ```console
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37 | pnpm add -D style-loader
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38 | ```
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39 |
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40 | It's recommended to combine `style-loader` with the [`css-loader`](https://github.com/webpack-contrib/css-loader)
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41 |
|
42 | Then add the loader to your `webpack` config. For example:
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43 |
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44 | **style.css**
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45 |
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46 | ```css
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47 | body {
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48 | background: green;
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49 | }
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50 | ```
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51 |
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52 | **component.js**
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53 |
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54 | ```js
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55 | import "./style.css";
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56 | ```
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57 |
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58 | **webpack.config.js**
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59 |
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60 | ```js
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61 | module.exports = {
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62 | module: {
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63 | rules: [
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64 | {
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65 | test: /\.css$/i,
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66 | use: ["style-loader", "css-loader"],
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67 | },
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68 | ],
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69 | },
|
70 | };
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71 | ```
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72 |
|
73 | ## Security Warning
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74 |
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75 | 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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76 |
|
77 | ## Options
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78 |
|
79 | - [**`injectType`**](#injecttype)
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80 | - [**`attributes`**](#attributes)
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81 | - [**`insert`**](#insert)
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82 | - [**`styleTagTransform`**](#styleTagTransform)
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83 | - [**`base`**](#base)
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84 | - [**`esModule`**](#esmodule)
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85 |
|
86 | ### `injectType`
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87 |
|
88 | Type:
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89 |
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90 | ```ts
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91 | type injectType =
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92 | | "styleTag"
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93 | | "singletonStyleTag"
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94 | | "autoStyleTag"
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95 | | "lazyStyleTag"
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96 | | "lazySingletonStyleTag"
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97 | | "lazyAutoStyleTag"
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98 | | "linkTag";
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99 | ```
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100 |
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101 | Default: `styleTag`
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102 |
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103 | Allows to setup how styles will be injected into the DOM.
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104 |
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105 | Possible values:
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106 |
|
107 | #### `styleTag`
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108 |
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109 | Automatically injects styles into the DOM using multiple `<style></style>`. It is **default** behaviour.
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110 |
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111 | **component.js**
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112 |
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113 | ```js
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114 | import "./styles.css";
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115 | ```
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116 |
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117 | Example with Locals (CSS Modules):
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118 |
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119 | **component-with-css-modules.js**
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120 |
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121 | ```js
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122 | import * as styles from "./styles.css";
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123 |
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124 | const divElement = document.createElement("div");
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125 | divElement.className = styles["my-class"];
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126 | ```
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127 |
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128 | 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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129 |
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130 | **webpack.config.js**
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131 |
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132 | ```js
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133 | module.exports = {
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134 | module: {
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135 | rules: [
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136 | {
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137 | test: /\.css$/i,
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138 | use: [
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139 | // The `injectType` option can be avoided because it is default behaviour
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140 | { loader: "style-loader", options: { injectType: "styleTag" } },
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141 | {
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142 | loader: "css-loader",
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143 | // Uncomment it if you want to use CSS modules
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144 | // options: { modules: true }
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145 | },
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146 | ],
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147 | },
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148 | ],
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149 | },
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150 | };
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151 | ```
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152 |
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153 | The loader inject styles like:
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154 |
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155 | ```html
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156 | <style>
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157 | .foo {
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158 | color: red;
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159 | }
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160 | </style>
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161 | <style>
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162 | .bar {
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163 | color: blue;
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164 | }
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165 | </style>
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166 | ```
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167 |
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168 | #### `singletonStyleTag`
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169 |
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170 | Automatically injects styles into the DOM using one `<style></style>`.
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171 |
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172 | > **Warning**
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173 | >
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174 | > Source maps do not work.
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175 |
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176 | **component.js**
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177 |
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178 | ```js
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179 | import "./styles.css";
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180 | ```
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181 |
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182 | **component-with-css-modules.js**
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183 |
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184 | ```js
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185 | import * as styles from "./styles.css";
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186 |
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187 | const divElement = document.createElement("div");
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188 | divElement.className = styles["my-class"];
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189 | ```
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190 |
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191 | 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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192 |
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193 | **webpack.config.js**
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194 |
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195 | ```js
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196 | module.exports = {
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197 | module: {
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198 | rules: [
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199 | {
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200 | test: /\.css$/i,
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201 | use: [
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202 | {
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203 | loader: "style-loader",
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204 | options: { injectType: "singletonStyleTag" },
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205 | },
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206 | {
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207 | loader: "css-loader",
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208 | // Uncomment it if you want to use CSS modules
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209 | // options: { modules: true }
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210 | },
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211 | ],
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212 | },
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213 | ],
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214 | },
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215 | };
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216 | ```
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217 |
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218 | The loader inject styles like:
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219 |
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220 | ```html
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221 | <style>
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222 | .foo {
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223 | color: red;
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224 | }
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225 | .bar {
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226 | color: blue;
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227 | }
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228 | </style>
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229 | ```
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230 |
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231 | #### `autoStyleTag`
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232 |
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233 | 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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234 |
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235 | #### `lazyStyleTag`
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236 |
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237 | Injects styles into the DOM using multiple `<style></style>` on demand.
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238 | 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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239 | When you `lazyStyleTag` value the `style-loader` injects the styles lazily making them useable on-demand via `style.use()` / `style.unuse()`.
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240 |
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241 | > ⚠️ Behavior is undefined when `unuse` is called more often than `use`. Don't do that.
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242 |
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243 | **component.js**
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244 |
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245 | ```js
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246 | import styles from "./styles.lazy.css";
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247 |
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248 | styles.use();
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249 | // For removing styles you can use
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250 | // styles.unuse();
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251 | ```
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252 |
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253 | **component-with-css-modules.js**
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254 |
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255 | ```js
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256 | import styles, { "my-class" as myClass } from "./styles.lazy.css";
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257 |
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258 | styles.use();
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259 |
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260 | const divElement = document.createElement("div");
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261 | divElement.className = myClass;
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262 | ```
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263 |
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264 | 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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265 |
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266 | **webpack.config.js**
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267 |
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268 | ```js
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269 | module.exports = {
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270 | module: {
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271 | rules: [
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272 | {
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273 | test: /\.css$/i,
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274 | exclude: /\.lazy\.css$/i,
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275 | use: ["style-loader", "css-loader"],
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276 | },
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277 | {
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278 | test: /\.lazy\.css$/i,
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279 | use: [
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280 | { loader: "style-loader", options: { injectType: "lazyStyleTag" } },
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281 | {
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282 | loader: "css-loader",
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283 | // Uncomment it if you want to use CSS modules
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284 | // options: { modules: true }
|
285 | },
|
286 | ],
|
287 | },
|
288 | ],
|
289 | },
|
290 | };
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291 | ```
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292 |
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293 | The loader inject styles like:
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294 |
|
295 | ```html
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296 | <style>
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297 | .foo {
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298 | color: red;
|
299 | }
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300 | </style>
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301 | <style>
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302 | .bar {
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303 | color: blue;
|
304 | }
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305 | </style>
|
306 | ```
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307 |
|
308 | #### `lazySingletonStyleTag`
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309 |
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310 | Injects styles into the DOM using one `<style></style>` on demand.
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311 | 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`).
|
312 | When you `lazySingletonStyleTag` value the `style-loader` injects the styles lazily making them useable on-demand via `style.use()` / `style.unuse()`.
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313 |
|
314 | > ⚠️ Source maps do not work.
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315 |
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316 | > ⚠️ Behavior is undefined when `unuse` is called more often than `use`. Don't do that.
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317 |
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318 | **component.js**
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319 |
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320 | ```js
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321 | import styles from "./styles.css";
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322 |
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323 | styles.use();
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324 | // For removing styles you can use
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325 | // styles.unuse();
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326 | ```
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327 |
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328 | **component-with-css-modules.js**
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329 |
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330 | ```js
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331 | import styles, { "my-class" as myClass } from "./styles.lazy.css";
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332 |
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333 | styles.use();
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334 |
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335 | const divElement = document.createElement("div");
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336 | divElement.className = myClass;
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337 | ```
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338 |
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339 | 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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340 |
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341 | **webpack.config.js**
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342 |
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343 | ```js
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344 | module.exports = {
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345 | module: {
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346 | rules: [
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347 | {
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348 | test: /\.css$/i,
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349 | exclude: /\.lazy\.css$/i,
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350 | use: ["style-loader", "css-loader"],
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351 | },
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352 | {
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353 | test: /\.lazy\.css$/i,
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354 | use: [
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355 | {
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356 | loader: "style-loader",
|
357 | options: { injectType: "lazySingletonStyleTag" },
|
358 | },
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359 | {
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360 | loader: "css-loader",
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361 | // Uncomment it if you want to use CSS modules
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362 | // options: { modules: true }
|
363 | },
|
364 | ],
|
365 | },
|
366 | ],
|
367 | },
|
368 | };
|
369 | ```
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370 |
|
371 | The loader generate this:
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372 |
|
373 | ```html
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374 | <style>
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375 | .foo {
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376 | color: red;
|
377 | }
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378 | .bar {
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379 | color: blue;
|
380 | }
|
381 | </style>
|
382 | ```
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383 |
|
384 | #### `lazyAutoStyleTag`
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385 |
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386 | Works the same as a [`lazyStyleTag`](#lazyStyleTag), but if the code is executed in IE6-9, turns on the [`lazySingletonStyleTag`](#lazySingletonStyleTag) mode.
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387 |
|
388 | #### `linkTag`
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389 |
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390 | Injects styles into the DOM using multiple `<link rel="stylesheet" href="path/to/file.css">` .
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391 |
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392 | > 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">`.
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393 |
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394 | ```js
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395 | import "./styles.css";
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396 | import "./other-styles.css";
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397 | ```
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398 |
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399 | **webpack.config.js**
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400 |
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401 | ```js
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402 | module.exports = {
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403 | module: {
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404 | rules: [
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405 | {
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406 | test: /\.link\.css$/i,
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407 | use: [
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408 | { loader: "style-loader", options: { injectType: "linkTag" } },
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409 | { loader: "file-loader" },
|
410 | ],
|
411 | },
|
412 | ],
|
413 | },
|
414 | };
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415 | ```
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416 |
|
417 | The loader generate this:
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418 |
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419 | ```html
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420 | <link rel="stylesheet" href="path/to/style.css" />
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421 | <link rel="stylesheet" href="path/to/other-styles.css" />
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422 | ```
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423 |
|
424 | ### `attributes`
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425 |
|
426 | Type:
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427 |
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428 | ```ts
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429 | type attributes = HTMLAttributes;
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430 | ```
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431 |
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432 | Default: `{}`
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433 |
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434 | If defined, the `style-loader` will attach given attributes with their values on `<style>` / `<link>` element.
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435 |
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436 | **component.js**
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437 |
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438 | ```js
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439 | import "./file.css";
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440 | ```
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441 |
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442 | **webpack.config.js**
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443 |
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444 | ```js
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445 | module.exports = {
|
446 | module: {
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447 | rules: [
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448 | {
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449 | test: /\.css$/i,
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450 | use: [
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451 | { loader: "style-loader", options: { attributes: { id: "id" } } },
|
452 | { loader: "css-loader" },
|
453 | ],
|
454 | },
|
455 | ],
|
456 | },
|
457 | };
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458 | ```
|
459 |
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460 | ```html
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461 | <style id="id"></style>
|
462 | ```
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463 |
|
464 | ### `insert`
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465 |
|
466 | Type:
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467 |
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468 | ```ts
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469 | type insert = string;
|
470 | ```
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471 |
|
472 | Default: `head`
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473 |
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474 | 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`.
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475 | This will cause CSS created by the loader to take priority over CSS already present in the target.
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476 | You can use other values if the standard behavior is not suitable for you, but we do not recommend doing this.
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477 | 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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478 |
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479 | #### `Selector`
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480 |
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481 | Allows to setup custom [query selector](https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelector) where styles inject into the DOM.
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482 |
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483 | **webpack.config.js**
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484 |
|
485 | ```js
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486 | module.exports = {
|
487 | module: {
|
488 | rules: [
|
489 | {
|
490 | test: /\.css$/i,
|
491 | use: [
|
492 | {
|
493 | loader: "style-loader",
|
494 | options: {
|
495 | insert: "body",
|
496 | },
|
497 | },
|
498 | "css-loader",
|
499 | ],
|
500 | },
|
501 | ],
|
502 | },
|
503 | };
|
504 | ```
|
505 |
|
506 | #### `Absolute path to function`
|
507 |
|
508 | Allows to setup absolute path to custom function that allows to override default behavior and insert styles at any position.
|
509 |
|
510 | > **Warning**
|
511 | >
|
512 | > 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.
|
513 |
|
514 | > **Warning**
|
515 | >
|
516 | > 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
|
517 |
|
518 | **webpack.config.js**
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519 |
|
520 | ```js
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521 | module.exports = {
|
522 | module: {
|
523 | rules: [
|
524 | {
|
525 | test: /\.css$/i,
|
526 | use: [
|
527 | {
|
528 | loader: "style-loader",
|
529 | options: {
|
530 | insert: require.resolve("./path-to-insert-module"),
|
531 | },
|
532 | },
|
533 | "css-loader",
|
534 | ],
|
535 | },
|
536 | ],
|
537 | },
|
538 | };
|
539 | ```
|
540 |
|
541 | A new `<style>`/`<link>` elements will be inserted into at bottom of `body` tag.
|
542 |
|
543 | Examples:
|
544 |
|
545 | Insert styles at top of `head` tag:
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546 |
|
547 | **insert-function.js**
|
548 |
|
549 | ```js
|
550 | function insertAtTop(element) {
|
551 | var parent = document.querySelector("head");
|
552 | // eslint-disable-next-line no-underscore-dangle
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553 | var lastInsertedElement = window._lastElementInsertedByStyleLoader;
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554 |
|
555 | if (!lastInsertedElement) {
|
556 | parent.insertBefore(element, parent.firstChild);
|
557 | } else if (lastInsertedElement.nextSibling) {
|
558 | parent.insertBefore(element, lastInsertedElement.nextSibling);
|
559 | } else {
|
560 | parent.appendChild(element);
|
561 | }
|
562 |
|
563 | // eslint-disable-next-line no-underscore-dangle
|
564 | window._lastElementInsertedByStyleLoader = element;
|
565 | }
|
566 |
|
567 | module.exports = insertAtTop;
|
568 | ```
|
569 |
|
570 | **webpack.config.js**
|
571 |
|
572 | ```js
|
573 | module.exports = {
|
574 | module: {
|
575 | rules: [
|
576 | {
|
577 | test: /\.css$/i,
|
578 | use: [
|
579 | {
|
580 | loader: "style-loader",
|
581 | options: {
|
582 | insert: require.resolve("./insert-function"),
|
583 | },
|
584 | },
|
585 | "css-loader",
|
586 | ],
|
587 | },
|
588 | ],
|
589 | },
|
590 | };
|
591 | ```
|
592 |
|
593 | You can pass any parameters to `style.use(options)` and this value will be passed to `insert` and `styleTagTransform` functions.
|
594 |
|
595 | **insert-function.js**
|
596 |
|
597 | ```js
|
598 | function insertIntoTarget(element, options) {
|
599 | var parent = options.target || document.head;
|
600 |
|
601 | parent.appendChild(element);
|
602 | }
|
603 |
|
604 | module.exports = insertIntoTarget;
|
605 | ```
|
606 |
|
607 | **webpack.config.js**
|
608 |
|
609 | ```js
|
610 | module.exports = {
|
611 | module: {
|
612 | rules: [
|
613 | {
|
614 | test: /\.css$/i,
|
615 | use: [
|
616 | {
|
617 | loader: "style-loader",
|
618 | options: {
|
619 | injectType: "lazyStyleTag",
|
620 | // Do not forget that this code will be used in the browser and
|
621 | // not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc,
|
622 | // we recommend use only ECMA 5 features,
|
623 | // but it depends what browsers you want to support
|
624 | insert: require.resolve("./insert-function.js"),
|
625 | },
|
626 | },
|
627 | "css-loader",
|
628 | ],
|
629 | },
|
630 | ],
|
631 | },
|
632 | };
|
633 | ```
|
634 |
|
635 | 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).
|
636 |
|
637 | **custom-square.css**
|
638 |
|
639 | ```css
|
640 | div {
|
641 | width: 50px;
|
642 | height: 50px;
|
643 | background-color: red;
|
644 | }
|
645 | ```
|
646 |
|
647 | **custom-square.js**
|
648 |
|
649 | ```js
|
650 | import customSquareStyles from "./custom-square.css";
|
651 |
|
652 | class CustomSquare extends HTMLElement {
|
653 | constructor() {
|
654 | super();
|
655 |
|
656 | this.attachShadow({ mode: "open" });
|
657 |
|
658 | const divElement = document.createElement("div");
|
659 |
|
660 | divElement.textContent = "Text content.";
|
661 |
|
662 | this.shadowRoot.appendChild(divElement);
|
663 |
|
664 | customSquareStyles.use({ target: this.shadowRoot });
|
665 |
|
666 | // You can override injected styles
|
667 | const bgPurple = new CSSStyleSheet();
|
668 | const width = this.getAttribute("w");
|
669 | const height = this.getAttribute("h");
|
670 |
|
671 | bgPurple.replace(`div { width: ${width}px; height: ${height}px; }`);
|
672 |
|
673 | this.shadowRoot.adoptedStyleSheets = [bgPurple];
|
674 |
|
675 | // `divElement` will have `100px` width, `100px` height and `red` background color
|
676 | }
|
677 | }
|
678 |
|
679 | customElements.define("custom-square", CustomSquare);
|
680 |
|
681 | export default CustomSquare;
|
682 | ```
|
683 |
|
684 | ### `styleTagTransform`
|
685 |
|
686 | Type:
|
687 |
|
688 | ```ts
|
689 | type styleTagTransform = string;
|
690 | ```
|
691 |
|
692 | Default: `undefined`
|
693 |
|
694 | #### `string`
|
695 |
|
696 | Allows to setup absolute path to custom function that allows to override default behavior styleTagTransform.
|
697 |
|
698 | > **Warning**
|
699 | >
|
700 | > Do not forget that this code will be used in the browser and not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc, we recommend use only ECMA 5 features, but it is depends what browsers you want to support
|
701 |
|
702 | > **Warning**
|
703 | >
|
704 | > Do not forget that some DOM methods may not be available in older browsers, we recommended use only [DOM core level 2 properties](https://caniuse.com/#search=DOM%20Core), but it depends what browsers you want to support
|
705 |
|
706 | **webpack.config.js**
|
707 |
|
708 | ```js
|
709 | module.exports = {
|
710 | module: {
|
711 | rules: [
|
712 | {
|
713 | test: /\.css$/i,
|
714 | use: [
|
715 | {
|
716 | loader: "style-loader",
|
717 | options: {
|
718 | injectType: "styleTag",
|
719 | styleTagTransform: require.resolve("style-tag-transform-code"),
|
720 | },
|
721 | },
|
722 | "css-loader",
|
723 | ],
|
724 | },
|
725 | ],
|
726 | },
|
727 | };
|
728 | ```
|
729 |
|
730 | ### `base`
|
731 |
|
732 | ```ts
|
733 | type base = number;
|
734 | ```
|
735 |
|
736 | 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.:
|
737 |
|
738 | **webpack.dll1.config.js**
|
739 |
|
740 | ```js
|
741 | module.exports = {
|
742 | module: {
|
743 | rules: [
|
744 | {
|
745 | test: /\.css$/i,
|
746 | use: ["style-loader", "css-loader"],
|
747 | },
|
748 | ],
|
749 | },
|
750 | };
|
751 | ```
|
752 |
|
753 | **webpack.dll2.config.js**
|
754 |
|
755 | ```js
|
756 | module.exports = {
|
757 | module: {
|
758 | rules: [
|
759 | {
|
760 | test: /\.css$/i,
|
761 | use: [
|
762 | { loader: "style-loader", options: { base: 1000 } },
|
763 | "css-loader",
|
764 | ],
|
765 | },
|
766 | ],
|
767 | },
|
768 | };
|
769 | ```
|
770 |
|
771 | **webpack.app.config.js**
|
772 |
|
773 | ```js
|
774 | module.exports = {
|
775 | module: {
|
776 | rules: [
|
777 | {
|
778 | test: /\.css$/i,
|
779 | use: [
|
780 | { loader: "style-loader", options: { base: 2000 } },
|
781 | "css-loader",
|
782 | ],
|
783 | },
|
784 | ],
|
785 | },
|
786 | };
|
787 | ```
|
788 |
|
789 | ### `esModule`
|
790 |
|
791 | Type:
|
792 |
|
793 | ```ts
|
794 | type esModule = boolean;
|
795 | ```
|
796 |
|
797 | Default: `true`
|
798 |
|
799 | By default, `style-loader` generates JS modules that use the ES modules syntax.
|
800 | There are some cases in which using ES modules is beneficial, like in the case of [module concatenation](https://webpack.js.org/plugins/module-concatenation-plugin/) and [tree shaking](https://webpack.js.org/guides/tree-shaking/).
|
801 |
|
802 | You can enable a CommonJS modules syntax using:
|
803 |
|
804 | **webpack.config.js**
|
805 |
|
806 | ```js
|
807 | module.exports = {
|
808 | module: {
|
809 | rules: [
|
810 | {
|
811 | test: /\.css$/i,
|
812 | loader: "style-loader",
|
813 | options: {
|
814 | esModule: false,
|
815 | },
|
816 | },
|
817 | ],
|
818 | },
|
819 | };
|
820 | ```
|
821 |
|
822 | ## Examples
|
823 |
|
824 | ### Recommend
|
825 |
|
826 | 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.
|
827 | 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.
|
828 | 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.
|
829 |
|
830 | > **Warning**
|
831 | >
|
832 | > Do not use together `style-loader` and `mini-css-extract-plugin`.
|
833 |
|
834 | **webpack.config.js**
|
835 |
|
836 | ```js
|
837 | const MiniCssExtractPlugin = require("mini-css-extract-plugin");
|
838 | const devMode = process.env.NODE_ENV !== "production";
|
839 |
|
840 | module.exports = {
|
841 | module: {
|
842 | rules: [
|
843 | {
|
844 | test: /\.(sa|sc|c)ss$/,
|
845 | use: [
|
846 | devMode ? "style-loader" : MiniCssExtractPlugin.loader,
|
847 | "css-loader",
|
848 | "postcss-loader",
|
849 | "sass-loader",
|
850 | ],
|
851 | },
|
852 | ],
|
853 | },
|
854 | plugins: [].concat(devMode ? [] : [new MiniCssExtractPlugin()]),
|
855 | };
|
856 | ```
|
857 |
|
858 | ### Named export for CSS Modules
|
859 |
|
860 | > **Warning**
|
861 | >
|
862 | > It is not allowed to use JavaScript reserved words in css class names.
|
863 |
|
864 | > **Warning**
|
865 | >
|
866 | > Options `esModule` and `modules.namedExport` in `css-loader` should be enabled (by default for `css-loader@7` it is true).
|
867 |
|
868 | **styles.css**
|
869 |
|
870 | ```css
|
871 | .fooBaz {
|
872 | color: red;
|
873 | }
|
874 | .bar {
|
875 | color: blue;
|
876 | }
|
877 | .my-class {
|
878 | color: green;
|
879 | }
|
880 | ```
|
881 |
|
882 | **index.js**
|
883 |
|
884 | ```js
|
885 | import { fooBaz, bar, "my-class" as myClass } from "./styles.css";
|
886 |
|
887 | console.log(fooBaz, bar, myClass);
|
888 | ```
|
889 |
|
890 | Or:
|
891 |
|
892 | **index.js**
|
893 |
|
894 | ```js
|
895 | import * as styles from "./styles.css";
|
896 |
|
897 | console.log(styles.fooBaz, styles.bar, styles["my-class"]);
|
898 | ```
|
899 |
|
900 | You can enable a ES module named export using:
|
901 |
|
902 | **webpack.config.js**
|
903 |
|
904 | ```js
|
905 | module.exports = {
|
906 | module: {
|
907 | rules: [
|
908 | {
|
909 | test: /\.css$/,
|
910 | use: [
|
911 | {
|
912 | loader: "style-loader",
|
913 | },
|
914 | {
|
915 | loader: "css-loader",
|
916 | options: {
|
917 | modules: {
|
918 | namedExport: true,
|
919 | },
|
920 | },
|
921 | },
|
922 | ],
|
923 | },
|
924 | ],
|
925 | },
|
926 | };
|
927 | ```
|
928 |
|
929 | ### Source maps
|
930 |
|
931 | The loader automatically inject source maps when previous loader emit them.
|
932 | Therefore, to generate source maps, set the `sourceMap` option to `true` for the previous loader.
|
933 |
|
934 | **webpack.config.js**
|
935 |
|
936 | ```js
|
937 | module.exports = {
|
938 | module: {
|
939 | rules: [
|
940 | {
|
941 | test: /\.css$/i,
|
942 | use: [
|
943 | "style-loader",
|
944 | { loader: "css-loader", options: { sourceMap: true } },
|
945 | ],
|
946 | },
|
947 | ],
|
948 | },
|
949 | };
|
950 | ```
|
951 |
|
952 | ### Nonce
|
953 |
|
954 | If you are using a [Content Security Policy](https://www.w3.org/TR/CSP3/) (CSP), the injected code will usually be blocked. A workaround is to use a nonce. Note, however, that using a nonce significantly reduces the protection provided by the CSP. You can read more about the security impact in [the specification](https://www.w3.org/TR/CSP3/#security-considerations). The better solution is not to use this loader in production.
|
955 |
|
956 | There are two ways to work with `nonce`:
|
957 |
|
958 | - using the `attributes` option
|
959 | - using the `__webpack_nonce__` variable
|
960 |
|
961 | > **Warning**
|
962 | >
|
963 | > the `attributes` option takes precedence over the `__webpack_nonce__` variable
|
964 |
|
965 | #### `attributes`
|
966 |
|
967 | **component.js**
|
968 |
|
969 | ```js
|
970 | import "./style.css";
|
971 | ```
|
972 |
|
973 | **webpack.config.js**
|
974 |
|
975 | ```js
|
976 | module.exports = {
|
977 | module: {
|
978 | rules: [
|
979 | {
|
980 | test: /\.css$/i,
|
981 | use: [
|
982 | {
|
983 | loader: "style-loader",
|
984 | options: {
|
985 | attributes: {
|
986 | nonce: "12345678",
|
987 | },
|
988 | },
|
989 | },
|
990 | "css-loader",
|
991 | ],
|
992 | },
|
993 | ],
|
994 | },
|
995 | };
|
996 | ```
|
997 |
|
998 | The loader generate:
|
999 |
|
1000 | ```html
|
1001 | <style nonce="12345678">
|
1002 | .foo {
|
1003 | color: red;
|
1004 | }
|
1005 | </style>
|
1006 | ```
|
1007 |
|
1008 | #### `__webpack_nonce__`
|
1009 |
|
1010 | **create-nonce.js**
|
1011 |
|
1012 | ```js
|
1013 | __webpack_nonce__ = "12345678";
|
1014 | ```
|
1015 |
|
1016 | **component.js**
|
1017 |
|
1018 | ```js
|
1019 | import "./create-nonce.js";
|
1020 | import "./style.css";
|
1021 | ```
|
1022 |
|
1023 | Alternative example for `require`:
|
1024 |
|
1025 | **component.js**
|
1026 |
|
1027 | ```js
|
1028 | __webpack_nonce__ = "12345678";
|
1029 |
|
1030 | require("./style.css");
|
1031 | ```
|
1032 |
|
1033 | **webpack.config.js**
|
1034 |
|
1035 | ```js
|
1036 | module.exports = {
|
1037 | module: {
|
1038 | rules: [
|
1039 | {
|
1040 | test: /\.css$/i,
|
1041 | use: ["style-loader", "css-loader"],
|
1042 | },
|
1043 | ],
|
1044 | },
|
1045 | };
|
1046 | ```
|
1047 |
|
1048 | The loader generate:
|
1049 |
|
1050 | ```html
|
1051 | <style nonce="12345678">
|
1052 | .foo {
|
1053 | color: red;
|
1054 | }
|
1055 | </style>
|
1056 | ```
|
1057 |
|
1058 | #### Insert styles at top
|
1059 |
|
1060 | Insert styles at top of `head` tag.
|
1061 |
|
1062 | **insert-function.js**
|
1063 |
|
1064 | ```js
|
1065 | function insertAtTop(element) {
|
1066 | var parent = document.querySelector("head");
|
1067 | var lastInsertedElement = window._lastElementInsertedByStyleLoader;
|
1068 |
|
1069 | if (!lastInsertedElement) {
|
1070 | parent.insertBefore(element, parent.firstChild);
|
1071 | } else if (lastInsertedElement.nextSibling) {
|
1072 | parent.insertBefore(element, lastInsertedElement.nextSibling);
|
1073 | } else {
|
1074 | parent.appendChild(element);
|
1075 | }
|
1076 |
|
1077 | window._lastElementInsertedByStyleLoader = element;
|
1078 | }
|
1079 |
|
1080 | module.exports = insertAtTop;
|
1081 | ```
|
1082 |
|
1083 | **webpack.config.js**
|
1084 |
|
1085 | ```js
|
1086 | module.exports = {
|
1087 | module: {
|
1088 | rules: [
|
1089 | {
|
1090 | test: /\.css$/i,
|
1091 | use: [
|
1092 | {
|
1093 | loader: "style-loader",
|
1094 | options: {
|
1095 | insert: require.resolve("./insert-function.js"),
|
1096 | },
|
1097 | },
|
1098 | "css-loader",
|
1099 | ],
|
1100 | },
|
1101 | ],
|
1102 | },
|
1103 | };
|
1104 | ```
|
1105 |
|
1106 | #### Insert styles before target element
|
1107 |
|
1108 | Inserts styles before `#id` element.
|
1109 |
|
1110 | **insert-function.js**
|
1111 |
|
1112 | ```js
|
1113 | function insertBeforeAt(element) {
|
1114 | const parent = document.querySelector("head");
|
1115 | const target = document.querySelector("#id");
|
1116 |
|
1117 | const lastInsertedElement = window._lastElementInsertedByStyleLoader;
|
1118 |
|
1119 | if (!lastInsertedElement) {
|
1120 | parent.insertBefore(element, target);
|
1121 | } else if (lastInsertedElement.nextSibling) {
|
1122 | parent.insertBefore(element, lastInsertedElement.nextSibling);
|
1123 | } else {
|
1124 | parent.appendChild(element);
|
1125 | }
|
1126 |
|
1127 | window._lastElementInsertedByStyleLoader = element;
|
1128 | }
|
1129 |
|
1130 | module.exports = insertBeforeAt;
|
1131 | ```
|
1132 |
|
1133 | **webpack.config.js**
|
1134 |
|
1135 | ```js
|
1136 | module.exports = {
|
1137 | module: {
|
1138 | rules: [
|
1139 | {
|
1140 | test: /\.css$/i,
|
1141 | use: [
|
1142 | {
|
1143 | loader: "style-loader",
|
1144 | options: {
|
1145 | insert: require.resolve("./insert-function.js"),
|
1146 | },
|
1147 | },
|
1148 | "css-loader",
|
1149 | ],
|
1150 | },
|
1151 | ],
|
1152 | },
|
1153 | };
|
1154 | ```
|
1155 |
|
1156 | #### Custom Elements (Shadow DOM)
|
1157 |
|
1158 | You can define custom target for your styles for the `lazyStyleTag` type.
|
1159 |
|
1160 | **insert-function.js**
|
1161 |
|
1162 | ```js
|
1163 | function insertIntoTarget(element, options) {
|
1164 | var parent = options.target || document.head;
|
1165 |
|
1166 | parent.appendChild(element);
|
1167 | }
|
1168 |
|
1169 | module.exports = insertIntoTarget;
|
1170 | ```
|
1171 |
|
1172 | **webpack.config.js**
|
1173 |
|
1174 | ```js
|
1175 | module.exports = {
|
1176 | module: {
|
1177 | rules: [
|
1178 | {
|
1179 | test: /\.css$/i,
|
1180 | use: [
|
1181 | {
|
1182 | loader: "style-loader",
|
1183 | options: {
|
1184 | injectType: "lazyStyleTag",
|
1185 | // Do not forget that this code will be used in the browser and
|
1186 | // not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc,
|
1187 | // we recommend use only ECMA 5 features,
|
1188 | // but it is depends what browsers you want to support
|
1189 | insert: require.resolve("./insert-function.js"),
|
1190 | },
|
1191 | },
|
1192 | "css-loader",
|
1193 | ],
|
1194 | },
|
1195 | ],
|
1196 | },
|
1197 | };
|
1198 | ```
|
1199 |
|
1200 | Insert styles to the provided element or to the `head` tag if target isn't provided.
|
1201 |
|
1202 | **custom-square.css**
|
1203 |
|
1204 | ```css
|
1205 | div {
|
1206 | width: 50px;
|
1207 | height: 50px;
|
1208 | background-color: red;
|
1209 | }
|
1210 | ```
|
1211 |
|
1212 | **custom-square.js**
|
1213 |
|
1214 | ```js
|
1215 | import customSquareStyles from "./custom-square.css";
|
1216 |
|
1217 | class CustomSquare extends HTMLElement {
|
1218 | constructor() {
|
1219 | super();
|
1220 |
|
1221 | this.attachShadow({ mode: "open" });
|
1222 |
|
1223 | const divElement = document.createElement("div");
|
1224 |
|
1225 | divElement.textContent = "Text content.";
|
1226 |
|
1227 | this.shadowRoot.appendChild(divElement);
|
1228 |
|
1229 | customSquareStyles.use({ target: this.shadowRoot });
|
1230 |
|
1231 | // You can override injected styles
|
1232 | const bgPurple = new CSSStyleSheet();
|
1233 | const width = this.getAttribute("w");
|
1234 | const height = this.getAttribute("h");
|
1235 |
|
1236 | bgPurple.replace(`div { width: ${width}px; height: ${height}px; }`);
|
1237 |
|
1238 | this.shadowRoot.adoptedStyleSheets = [bgPurple];
|
1239 |
|
1240 | // `divElement` will have `100px` width, `100px` height and `red` background color
|
1241 | }
|
1242 | }
|
1243 |
|
1244 | customElements.define("custom-square", CustomSquare);
|
1245 |
|
1246 | export default CustomSquare;
|
1247 | ```
|
1248 |
|
1249 | ## Contributing
|
1250 |
|
1251 | Please take a moment to read our contributing guidelines if you haven't yet done so.
|
1252 |
|
1253 | [CONTRIBUTING](./.github/CONTRIBUTING.md)
|
1254 |
|
1255 | ## License
|
1256 |
|
1257 | [MIT](./LICENSE)
|
1258 |
|
1259 | [npm]: https://img.shields.io/npm/v/style-loader.svg
|
1260 | [npm-url]: https://npmjs.com/package/style-loader
|
1261 | [node]: https://img.shields.io/node/v/style-loader.svg
|
1262 | [node-url]: https://nodejs.org
|
1263 | [tests]: https://github.com/webpack-contrib/style-loader/workflows/style-loader/badge.svg
|
1264 | [tests-url]: https://github.com/webpack-contrib/style-loader/actions
|
1265 | [cover]: https://codecov.io/gh/webpack-contrib/style-loader/branch/master/graph/badge.svg
|
1266 | [cover-url]: https://codecov.io/gh/webpack-contrib/style-loader
|
1267 | [discussion]: https://img.shields.io/github/discussions/webpack/webpack
|
1268 | [discussion-url]: https://github.com/webpack/webpack/discussions
|
1269 | [size]: https://packagephobia.now.sh/badge?p=style-loader
|
1270 | [size-url]: https://packagephobia.now.sh/result?p=style-loader
|