Sass loader for webpack

Install

npm install sass-loader --save-dev

Starting with 1.0.0, the sass-loader requires node-sass as peerDependency. Thus you are able to specify the required version accurately.

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Usage

Documentation: Using loaders

var css = require('!raw!sass!./file.scss');
// => returns compiled css code from file.scss, resolves imports
var css = require('!css!sass!./file.scss');
// => returns compiled css code from file.scss, resolves imports and url(...)s

Use in tandem with the style-loader and css-loader to add the css rules to your document:

require('!style!css!sass!./file.scss');

NOTE: If you encounter module errors complaining about a missing style or css module, make sure you have installed all required loaders via npm.

Apply via webpack config

It's recommended to adjust your webpack.config so style!css!sass! is applied automatically on all files ending on .scss:

module.exports = {
  module: {
    loaders: [
      {
        test: /\.scss$/,
        loader: 'style!css!sass'
      }
    ]
  }
};

Then you only need to write: require('./file.scss').

Sass options

You can pass any Sass specific configuration options through to the render function via query parameters.

module.exports = {
  module: {
    loaders: [
      {
        test: /\.scss$/,
        loader: "style!css!sass?outputStyle=expanded&" +
          "includePaths[]=" +
            encodeURIComponent(path.resolve(__dirname, "./some-folder")) + "&" +
          "includePaths[]=" +
            encodeURIComponent(path.resolve(__dirname, "./another-folder"))
      }
    ]
  }
};

See node-sass for all available options.

Imports

webpack provides an advanced mechanism to resolve files. The sass-loader uses node-sass' 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 ~ which tells webpack to look-up the modulesDirectories.

@import "~bootstrap/less/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";

.sass files

For requiring .sass files, add indentedSyntax as a loader option:

module.exports = {
  module: {
    loaders: [
      {
        test: /\.sass$/,
        // Passing indentedSyntax query param to node-sass
        loader: "style!css!sass?indentedSyntax"
      }
    ]
  }
};

Problems with url(...)

Since Sass/libsass does not provide url rewriting, 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. Place it directly after 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.

Source maps

Because of browser limitations, source maps are only available in conjunction with the extract-text-webpack-plugin. Use that plugin to extract the CSS code from the generated JS bundle into a separate file (which even improves the perceived performance because JS and CSS are downloaded in parallel).

Then your webpack.config.js should look like this:

var ExtractTextPlugin = require('extract-text-webpack-plugin');

module.exports = {
    ...
    // must be 'source-map' or 'inline-source-map'
    devtool: 'source-map',
    module: {
        loaders: [
            {
                test: /\.scss$/,
                loader: ExtractTextPlugin.extract(
                    // activate source maps via loader query
                    'css?sourceMap!' +
                    'sass?sourceMap'
                )
            }
        ]
    },
    plugins: [
        // extract inline css into separate 'styles.css'
        new ExtractTextPlugin('styles.css')
    ]
};

If you want to edit the original Sass files inside Chrome, there's a good blog post. Checkout test/sourceMap for a running example. Make sure to serve the content with an HTTP server.

License

MIT (http://www.opensource.org/licenses/mit-license.php)