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Sass Loader

Loads a Sass/SCSS file and compiles it to CSS.

Use the [css-loader](https://github.com/webpack-contrib/css-loader) or the [raw-loader](https://github.com/webpack-contrib/raw-loader) to turn it into a JS module and the [MiniCssExtractPlugin](https://github.com/webpack-contrib/mini-css-extract-plugin) to extract it into a separate file. Looking for the webpack 1 loader? Check out the [archive/webpack-1 branch](https://github.com/webpack-contrib/sass-loader/tree/archive/webpack-1).

Install

```bash npm install sass-loader node-sass webpack --save-dev ``` The sass-loader requires [webpack](https://github.com/webpack) as a [`peerDependency`](https://docs.npmjs.com/files/package.json#peerdependencies) and it requires you to install either [Node Sass][] or [Dart Sass][] on your own. This allows you to control the versions of all your dependencies, and to choose which Sass implementation to use. [Node Sass]: https://github.com/sass/node-sass [Dart Sass]: http://sass-lang.com/dart-sass

Examples

Chain the sass-loader with the [css-loader](https://github.com/webpack-contrib/css-loader) and the [style-loader](https://github.com/webpack-contrib/style-loader) to immediately apply all styles to the DOM. ```bash npm install style-loader css-loader --save-dev ``` ```js // webpack.config.js module.exports = { ... module: { rules: [{ test: /\.scss$/, use: [ "style-loader", // creates style nodes from JS strings "css-loader", // translates CSS into CommonJS "sass-loader" // compiles Sass to CSS, using Node Sass by default ] }] } }; ``` You can also pass options directly to [Node Sass][] or [Dart Sass][]: ```js // webpack.config.js module.exports = { ... module: { rules: [{ test: /\.scss$/, use: [{ loader: "style-loader" }, { loader: "css-loader" }, { loader: "sass-loader", options: { includePaths: ["absolute/path/a", "absolute/path/b"] } }] }] } }; ``` See [the Node Sass documentation](https://github.com/sass/node-sass/blob/master/README.md#options) for all available Sass options. The special `implementation` option determines which implementation of Sass to use. It takes either a [Node Sass][] or a [Dart Sass][] module. For example, to use Dart Sass, you'd pass: ```js // ... { loader: "sass-loader", options: { implementation: require("sass") } } // ... ``` Note that when using Dart Sass, **synchronous compilation is twice as fast as asynchronous compilation** by default, due to the overhead of asynchronous callbacks. To avoid this overhead, you can use the [`fibers`](https://www.npmjs.com/package/fibers) package to call asynchronous importers from the synchronous code path. To enable this, pass the `Fiber` class to the `fiber` option: ```js // webpack.config.js const Fiber = require('fibers'); module.exports = { ... module: { rules: [{ test: /\.scss$/, use: [{ loader: "style-loader" }, { loader: "css-loader" }, { loader: "sass-loader", options: { implementation: require("sass"), fiber: Fiber } }] }] } }; ``` ### In production Usually, it's recommended to extract the style sheets into a dedicated file in production using the [MiniCssExtractPlugin](https://github.com/webpack-contrib/mini-css-extract-plugin). This way your styles are not dependent on JavaScript: ```js const MiniCssExtractPlugin = require("mini-css-extract-plugin"); module.exports = { ... module: { rules: [{ test: /\.scss$/, use: [ // fallback to style-loader in development process.env.NODE_ENV !== 'production' ? 'style-loader' : MiniCssExtractPlugin.loader, "css-loader", "sass-loader" ] }] }, plugins: [ new MiniCssExtractPlugin({ // Options similar to the same options in webpackOptions.output // both options are optional filename: "[name].css", chunkFilename: "[id].css" }) ] }; ```

Usage

### Imports webpack provides an [advanced mechanism to resolve files](https://webpack.js.org/concepts/module-resolution/). The sass-loader uses Sass's custom importer feature to pass all queries to the webpack resolving engine. Thus you can import your Sass modules from `node_modules`. Just prepend them with a `~` to tell webpack that this is not a relative import: ```css @import "~bootstrap/dist/css/bootstrap"; ``` It's important to only prepend it with `~`, because `~/` resolves to the home directory. webpack needs to distinguish between `bootstrap` and `~bootstrap` because CSS and Sass files have no special syntax for importing relative files. Writing `@import "file"` is the same as `@import "./file";` ### Problems with `url(...)` Since Sass/[libsass](https://github.com/sass/libsass) does not provide [url rewriting](https://github.com/sass/libsass/issues/532), all linked assets must be relative to the output. - If you're just generating CSS without passing it to the css-loader, it must be relative to your web root. - If you pass the generated CSS on to the css-loader, all urls must be relative to the entry-file (e.g. `main.scss`). More likely you will be disrupted by this second issue. It is natural to expect relative references to be resolved against the `.scss` file in which they are specified (like in regular `.css` files). Thankfully there are a two solutions to this problem: - Add the missing url rewriting using the [resolve-url-loader](https://github.com/bholloway/resolve-url-loader). Place it before the sass-loader in the loader chain. - Library authors usually provide a variable to modify the asset path. [bootstrap-sass](https://github.com/twbs/bootstrap-sass) for example has an `$icon-font-path`. Check out [this working bootstrap example](https://github.com/webpack-contrib/sass-loader/tree/master/test/bootstrapSass). ### Extracting style sheets Bundling CSS with webpack has some nice advantages like referencing images and fonts with hashed urls or [hot module replacement](https://webpack.js.org/concepts/hot-module-replacement/) in development. In production, on the other hand, it's not a good idea to apply your style sheets depending on JS execution. Rendering may be delayed or even a [FOUC](https://en.wikipedia.org/wiki/Flash_of_unstyled_content) might be visible. Thus it's often still better to have them as separate files in your final production build. There are two possibilities to extract a style sheet from the bundle: - [extract-loader](https://github.com/peerigon/extract-loader) (simpler, but specialized on the css-loader's output) - [extract-text-webpack-plugin](https://github.com/webpack-contrib/extract-text-webpack-plugin) (more complex, but works in all use-cases) ### Source maps To enable CSS source maps, you'll need to pass the `sourceMap` option to the sass-loader *and* the css-loader. Your `webpack.config.js` should look like this: ```javascript module.exports = { ... devtool: "source-map", // any "source-map"-like devtool is possible module: { rules: [{ test: /\.scss$/, use: [{ loader: "style-loader" }, { loader: "css-loader", options: { sourceMap: true } }, { loader: "sass-loader", options: { sourceMap: true } }] }] } }; ``` If you want to edit the original Sass files inside Chrome, [there's a good blog post](https://medium.com/@toolmantim/getting-started-with-css-sourcemaps-and-in-browser-sass-editing-b4daab987fb0). Checkout [test/sourceMap](https://github.com/webpack-contrib/sass-loader/tree/master/test) for a running example. ### Environment variables If you want to prepend Sass code before the actual entry file, you can set the `data` option. In this case, the sass-loader will not override the `data` option but just append the entry's content. This is especially useful when some of your Sass variables depend on the environment: ```javascript { loader: "sass-loader", options: { data: "$env: " + process.env.NODE_ENV + ";" } } ``` **Please note:** Since you're injecting code, this will break the source mappings in your entry file. Often there's a simpler solution than this, like multiple Sass entry files.

Maintainers


Johannes Ewald
Jorik Tangelder
Kiran

License

[MIT](http://www.opensource.org/licenses/mit-license.php) [npm]: https://img.shields.io/npm/v/sass-loader.svg [npm-stats]: https://img.shields.io/npm/dm/sass-loader.svg [npm-url]: https://npmjs.com/package/sass-loader [node]: https://img.shields.io/node/v/sass-loader.svg [node-url]: https://nodejs.org [deps]: https://david-dm.org/webpack-contrib/sass-loader.svg [deps-url]: https://david-dm.org/webpack-contrib/sass-loader [travis]: http://img.shields.io/travis/webpack-contrib/sass-loader.svg [travis-url]: https://travis-ci.org/webpack-contrib/sass-loader [appveyor-url]: https://ci.appveyor.com/project/webpack-contrib/sass-loader/branch/master [appveyor]: https://ci.appveyor.com/api/projects/status/rqpy1vaovh20ttxs/branch/master?svg=true [cover]: https://codecov.io/gh/webpack-contrib/sass-loader/branch/master/graph/badge.svg [cover-url]: https://codecov.io/gh/webpack-contrib/sass-loader [chat]: https://badges.gitter.im/webpack/webpack.svg [chat-url]: https://gitter.im/webpack/webpack