Webpack Sass / Scss compiling to separate file

Webpack is an amazing tool for transpiling and bundling JavaScript, but it can also take care of compiling Sass or Scss to static files.

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I came across this issue while developing a prototype and not a single page app, that I needed to have a .scss file include some other files and output a .css file. I didn't need inlined and scoped CSS like one would probably do with a single page app.

This took me surprisingly long to figure this out, mostly because there is a lot of varying information out there and not a lot of good examples that work with the up to date versions of webpack 2 RC 4 and the ExtractTextPlugin.

First of all, I recommend you globally install a recent webpack version:

npm -g install [email protected]

Inside your project you need to install the following dependencies, remember to append the --save flag if you want them to be written to your package.json:

npm install css-loader node-sass sass-loader [email protected]

Now let's say we have a project structure for a simple one-page that looks like the following (identical to the example project):

├── app.js
├── package.json
├── scss
│   ├── about
│   │   └── about.scss
│   └── main.scss
├── webpack.config.js

• app.js contains all our cool JavaScript code
• package.json defines our dependencies
• scss/main.scss is our scss / sass entry point
• webpack.config.js is our config that tells webpack what to do

If you have cloned the example repository, after running the build with webpack it should look like the following:

├── app.js
├── dist
│   ├── bundle.js
│   └── main.bundle.css
├── package.json
├── scss
│   ├── about
│   │   └── about.scss
│   └── main.scss
├── webpack.config.js

Note: Frequently developers use npm run dev or npm run build to execute the webpack command.

Notice that the directory dist including the files bundle.js and main.bundle.css have been added. The latter contains the compiled SCSS from main.scss and about.scss.

Webpack SCSS / SASS config

Typically webpack processes everything in an input file and what ever is required by that file or other files that are required from there. It builds a tree of requirements, scoops up all the JavaScript and other resources and compiles them for you. If you want to just have it look for a file, we need to use the ExtractTextPlugin to process it.

Have a look at the config for this project below:

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

module.exports = {
  entry: ['./app.js', './scss/main.scss'],
  output: {
    filename: 'dist/bundle.js'
  },
  module: {

    rules: [
      /*
      your other rules for JavaScript transpiling go in here
      */
      { // regular css files
        test: /\.css$/,
        loader: ExtractTextPlugin.extract({
          loader: 'css-loader?importLoaders=1',
        }),
      },
      { // sass / scss loader for webpack
        test: /\.(sass|scss)$/,
        loader: ExtractTextPlugin.extract(['css-loader', 'sass-loader'])
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin({ // define where to save the file
      filename: 'dist/[name].bundle.css',
      allChunks: true,
    }),
  ],
};

The config that enables us to compile SCSS/SASS from a file instead of requiring it in our JavaScript source is the loaders that refer to ExtractTextPlugin and the plugin that specifies where to write the file.

Also note that in our entry points, we specify that ./scss/main.scss should be read and then run through the rules (in this case .scss would match).

Transpiled SCSS file

Congratulations, now our .scss files that used to look like this:

main.scss

// include another .scss file from a sub-directory
@import './about/about.scss';

body {
    a {
        color: magenta;
    }
}

about/about.scss

body {
    p {
        line-height: 1.5;
    }
}

Should be transpiled into a plain css file:

body p {
  line-height: 1.5; }

body a {
  color: magenta; }

Thank you so much for reading this post, I hope it was useful to you! Consider following me on twitter, feedly or instagram!

If anything doesn't work, please leave a comment and I'll have a look!