style-loader
Inject CSS into the DOM.
Getting Started
To begin, you'll need to install style-loader:
npm install --save-dev style-loader
It's recommended to combine style-loader with the css-loader
Then add the loader to your webpack config. For example:
style.css
body {
background: green;
}
component.js
import './style.css';
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: ['style-loader', 'css-loader'],
},
],
},
};
Options, Name, Type, Default, Description, :--------------:, :------------------:, :--------:, :-------------------------------------------------------, injectType, {String}, styleTag, Allows to setup how styles will be injected into the DOM, attributes, {Object}, {}, Adds custom attributes to tag, insert, {String\, Function}, head, Inserts tag at the given position into the DOM, base, {Number}, true, Sets module ID base (DLLPlugin), esModule, {Boolean}, false, Use ES modules syntax, ### injectType
Type: String
Default: styleTag
Allows to setup how styles will be injected into the DOM.
Possible values:
styleTagsingletonStyleTaglazyStyleTaglazySingletonStyleTaglinkTag
styleTag
Automatically injects styles into the DOM using multiple <style></style>. It is default behaviour.
component.js
import './styles.css';
Example with Locals (CSS Modules):
component-with-css-modules.js
import styles from './styles.css';
const divElement = document.createElement('div');
divElement.className = styles['my-class'];
All locals (class names) stored in imported object.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
// The `injectType` option can be avoided because it is default behaviour
{ loader: 'style-loader', options: { injectType: 'styleTag' } },
'css-loader',
],
},
],
},
};
The loader inject styles like:
<style>
.foo {
color: red;
}
</style>
<style>
.bar {
color: blue;
}
</style>
singletonStyleTag
Automatically injects styles into the DOM using one <style></style>.
⚠ Source maps do not work.
component.js
import './styles.css';
component-with-css-modules.js
import styles from './styles.css';
const divElement = document.createElement('div');
divElement.className = styles['my-class'];
All locals (class names) stored in imported object.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: 'style-loader',
options: { injectType: 'singletonStyleTag' },
},
'css-loader',
],
},
],
},
};
The loader inject styles like:
<style>
.foo {
color: red;
}
.bar {
color: blue;
}
</style>
lazyStyleTag
Injects styles into the DOM using multiple <style></style> on demand.
We recommend following .lazy.css naming convention for lazy styles and the .css for basic style-loader usage (similar to other file types, i.e. .lazy.less and .less).
When you lazyStyleTag value the style-loader injects the styles lazily making them useable on-demand via style.use() / style.unuse().
⚠️ Behavior is undefined when
unuseis called more often thanuse. Don't do that.
component.js
import styles from './styles.lazy.css';
styles.use();
// For removing styles you can use
// styles.unuse();
component-with-css-modules.js
import styles from './styles.lazy.css';
styles.use();
const divElement = document.createElement('div');
divElement.className = styles.locals['my-class'];
All locals (class names) stored in locals property of imported object.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
exclude: /\.lazy\.css$/i,
use: ['style-loader', 'css-loader'],
},
{
test: /\.lazy\.css$/i,
use: [
{ loader: 'style-loader', options: { injectType: 'lazyStyleTag' } },
'css-loader',
],
},
],
},
};
The loader inject styles like:
<style>
.foo {
color: red;
}
</style>
<style>
.bar {
color: blue;
}
</style>
lazySingletonStyleTag
Injects styles into the DOM using one <style></style> on demand.
We recommend following .lazy.css naming convention for lazy styles and the .css for basic style-loader usage (similar to other file types, i.e. .lazy.less and .less).
When you lazySingletonStyleTag value the style-loader injects the styles lazily making them useable on-demand via style.use() / style.unuse().
⚠️ Source maps do not work.
⚠️ Behavior is undefined when
unuseis called more often thanuse. Don't do that.
component.js
import styles from './styles.css';
styles.use();
// For removing styles you can use
// styles.unuse();
component-with-css-modules.js
import styles from './styles.lazy.css';
styles.use();
const divElement = document.createElement('div');
divElement.className = styles.locals['my-class'];
All locals (class names) stored in locals property of imported object.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
exclude: /\.lazy\.css$/i,
use: ['style-loader', 'css-loader'],
},
{
test: /\.lazy\.css$/i,
use: [
{
loader: 'style-loader',
options: { injectType: 'lazySingletonStyleTag' },
},
'css-loader',
],
},
],
},
};
The loader generate this:
<style>
.foo {
color: red;
}
.bar {
color: blue;
}
</style>
linkTag
Injects styles into the DOM using multiple <link rel="stylesheet" href="path/to/file.css"> .
ℹ️ The loader will dynamically insert the
<link href="path/to/file.css" rel="stylesheet">tag at runtime via JavaScript. You should use MiniCssExtractPlugin if you want to include a static<link href="path/to/file.css" rel="stylesheet">.
import './styles.css';
import './other-styles.css';
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.link\.css$/i,
use: [
{ loader: 'style-loader', options: { injectType: 'linkTag' } },
{ loader: 'file-loader' },
],
},
],
},
};
The loader generate this:
<link rel="stylesheet" href="path/to/style.css" />
<link rel="stylesheet" href="path/to/other-styles.css" />
attributes
Type: Object
Default: {}
If defined, the style-loader will attach given attributes with their values on <style> / <link> element.
component.js
import style from './file.css';
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{ loader: 'style-loader', options: { attributes: { id: 'id' } } },
{ loader: 'css-loader' },
],
},
],
},
};
<style id="id"></style>
insert
Type: String, Function
Default: head
By default, the style-loader appends <style>/<link> elements to the end of the style target, which is the <head> tag of the page unless specified by insert.
This will cause CSS created by the loader to take priority over CSS already present in the target.
You can use other values if the standard behavior is not suitable for you, but we do not recommend doing this.
If you target an iframe make sure you have sufficient access rights, the styles will be injected into the content document head.
String
Allows to setup custom query selector where styles inject into the DOM.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: 'style-loader',
options: {
insert: 'body',
},
},
'css-loader',
],
},
],
},
};
A new <style>/<link> elements will be inserted into at bottom of body tag.
Function
Allows to override default behavior and insert styles at any position.
⚠ 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 expressionand etc, we recommend use only ECMA 5 features, but it is depends what browsers you want to support
⚠ Do not forget that some DOM methods may not be available in older browsers, we recommended use only DOM core level 2 properties, but it is depends what browsers you want to support
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: 'style-loader',
options: {
insert: function insertAtTop(element) {
var parent = document.querySelector('head');
// eslint-disable-next-line no-underscore-dangle
var lastInsertedElement =
window._lastElementInsertedByStyleLoader;
if (!lastInsertedElement) {
parent.insertBefore(element, parent.firstChild);
} else if (lastInsertedElement.nextSibling) {
parent.insertBefore(element, lastInsertedElement.nextSibling);
} else {
parent.appendChild(element);
}
// eslint-disable-next-line no-underscore-dangle
window._lastElementInsertedByStyleLoader = element;
},
},
},
'css-loader',
],
},
],
},
};
Insert styles at top of head tag.
base
This setting is primarily used as a workaround for css clashes when using one or more DllPlugin's. base allows you to prevent either the app's css (or DllPlugin2's css) from overwriting DllPlugin1's css by specifying a css module id base which is greater than the range used by DllPlugin1 e.g.:
webpack.dll1.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: ['style-loader', 'css-loader'],
},
],
},
};
webpack.dll2.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{ loader: 'style-loader', options: { base: 1000 } },
'css-loader',
],
},
],
},
};
webpack.app.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{ loader: 'style-loader', options: { base: 2000 } },
'css-loader',
],
},
],
},
};
esModule
Type: Boolean
Default: false
By default, style-loader generates JS modules that use the CommonJS modules syntax.
There are some cases in which using ES modules is beneficial, like in the case of module concatenation and tree shaking.
You can enable a ES module syntax using:
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
loader: 'css-loader',
options: {
esModule: true,
},
},
],
},
};
Examples
Source maps
The loader automatically inject source maps when previous loader emit them.
Therefore, to generate source maps, set the sourceMap option to true for the previous loader.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
'style-loader',
{ loader: 'css-loader', options: { sourceMap: true } },
],
},
],
},
};
Nonce
There are two ways to work with nonce:
- using the
attributesoption - using the
__webpack_nonce__variable
⚠ the
attributesoption takes precedence over the__webpack_nonce__variable
attributes
component.js
import './style.css';
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: 'style-loader',
options: {
attributes: {
nonce: '12345678',
},
},
},
'css-loader',
],
},
],
},
};
The loader generate:
<style nonce="12345678">
.foo {
color: red;
}
</style>
__webpack_nonce__
create-nonce.js
__webpack_nonce__ = '12345678';
component.js
import './create-nonce.js';
import './style.css';
Alternative example for require:
component.js
__webpack_nonce__ = '12345678';
require('./style.css');
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: ['style-loader', 'css-loader'],
},
],
},
};
The loader generate:
<style nonce="12345678">
.foo {
color: red;
}
</style>
Insert styles at top
Inserts styles at top of head tag.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: 'style-loader',
options: {
insert: function insertAtTop(element) {
var parent = document.querySelector('head');
var lastInsertedElement =
window._lastElementInsertedByStyleLoader;
if (!lastInsertedElement) {
parent.insertBefore(element, parent.firstChild);
} else if (lastInsertedElement.nextSibling) {
parent.insertBefore(element, lastInsertedElement.nextSibling);
} else {
parent.appendChild(element);
}
window._lastElementInsertedByStyleLoader = element;
},
},
},
'css-loader',
],
},
],
},
};
Insert styles before target element
Inserts styles before #id element.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: 'style-loader',
options: {
insert: function insertBeforeAt(element) {
const parent = document.querySelector('head');
const target = document.querySelector('#id');
const lastInsertedElement =
window._lastElementInsertedByStyleLoader;
if (!lastInsertedElement) {
parent.insertBefore(element, target);
} else if (lastInsertedElement.nextSibling) {
parent.insertBefore(element, lastInsertedElement.nextSibling);
} else {
parent.appendChild(element);
}
window._lastElementInsertedByStyleLoader = element;
},
},
},
'css-loader',
],
},
],
},
};
Contributing
Please take a moment to read our contributing guidelines if you haven't yet done so.