sass-loader7.1.0 • Public • Published
Use the css-loader or the raw-loader to turn it into a JS module and the MiniCssExtractPlugin to extract it into a separate file. Looking for the webpack 1 loader? Check out the archive/webpack-1 branch.
npm install sass-loader node-sass webpack --save-dev
The sass-loader requires webpack as a
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.
npm install style-loader css-loader --save-dev
// webpack.config.jsmoduleexports =...module:rules:test: /\.scss$/use:"style-loader" // creates style nodes from JS strings"css-loader" // translates CSS into CommonJS"sass-loader" // compiles Sass to CSS, using Node Sass by default;
// webpack.config.jsmoduleexports =...module:rules:test: /\.scss$/use:loader: "style-loader"loader: "css-loader"loader: "sass-loader"options:includePaths: "absolute/path/a" "absolute/path/b";
See the Node Sass documentation for all available Sass options.
// ...loader: "sass-loader"options:implementation:// ...
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 package to call asynchronous
importers from the synchronous code path. To enable this, pass the
// webpack.config.jsconst Fiber = ;moduleexports =...module:rules:test: /\.scss$/use:loader: "style-loader"loader: "css-loader"loader: "sass-loader"options:implementation:fiber: Fiber;
const MiniCssExtractPlugin = ;moduleexports =...module:rules:test: /\.scss$/use:// fallback to style-loader in developmentprocessenvNODE_ENV !== 'production' ? 'style-loader' : MiniCssExtractPluginloader"css-loader""sass-loader"plugins:// Options similar to the same options in webpackOptions.output// both options are optionalfilename: "[name].css"chunkFilename: "[id].css";
webpack provides an advanced mechanism to resolve files. 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:
It's important to only prepend it with
~/ resolves to the home directory. webpack needs to distinguish between
~bootstrap because CSS and Sass files have no special syntax for importing relative files. Writing
@import "file" is the same as
- 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.
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. Place it before the sass-loader in the loader chain.
- Library authors usually provide a variable to modify the asset path. bootstrap-sass for example has an
$icon-font-path. Check out this working bootstrap example.
Extracting style sheets
Bundling CSS with webpack has some nice advantages like referencing images and fonts with hashed urls or hot module replacement in development. In production, on the other hand, it's not a good idea to apply your style sheets depending on JS execution. Rendering may be delayed or even a FOUC might be visible. Thus it's often still better to have them as separate files in your final production build.
There are two possibilities to extract a style sheet from the bundle:
- extract-loader (simpler, but specialized on the css-loader's output)
- extract-text-webpack-plugin (more complex, but works in all use-cases)
To enable CSS source maps, you'll need to pass the
sourceMap option to the sass-loader and the css-loader. Your
webpack.config.js should look like this:
moduleexports =...devtool: "source-map" // any "source-map"-like devtool is possiblemodule:rules:test: /\.scss$/use:loader: "style-loader"loader: "css-loader" options:sourceMap: trueloader: "sass-loader" options:sourceMap: true;
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:
loader: "sass-loader"options:data: "$env: " + processenvNODE_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.