Webpack - Export SASS (.scss) files

Question

I have a package and i want export my SASS variables to other packages use it. Currently my all .scss files are compiles and put in /dist/main.css file. My webpack config:

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

module.exports = {
  entry: ['./src/index.js'],
  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        loader: 'babel'
      },
      {
        test:   /\.(scss|sass|css)$/,
        loader: ExtractTextPlugin.extract("style", "css!sass")
      },
      {
        test: /\.(png|woff|woff2|eot|ttf|svg)$/,
        loader: 'url-loader?limit=10000&name=fonts/[hash].[ext]'
      },
      {
        test: /\.scss$/, loader: 'style!css!sass!sass-resources'
      }
    ]
  },
  resolve: {
    extensions: ['', '.js', '.jsx']
  },
  output: {
    path: __dirname + '/build',
    publicPath: '/',
    filename: 'index.js',
    library: 'Supernova',
    libraryTarget: 'umd'
  },
  externals: {
    'react': 'react',
    'react-dom': 'react-dom'
  },
  plugins: [
    new ExtractTextPlugin("[name].css")
  ]
};

My objective is create a package like bootstrap-sass.

Answer 1

If you want to make the variables you use within your sass files available to consumers of your published package, then you'll need to look at some special configuration for node-sass.

Currently (and as of the time you posted this) node-sass supports writing your own custom sass functions in javascript: https://github.com/sass/node-sass#functions--v300---experimental

This is untested, but we did this a while ago at a company i worked for...to do what you want, you'd need something like:

src/
  your-package.js
  your-styles.scss

tools/
  constants/
    colours.js

  webpack/
    ...
    base.sass.js
    base.js
    development.js
    production.js

  sass/
    functions/
      colours.js

# tools/webpack/base.sass.js

const Config = require('webpack-config').default

import {
  signature as ColourSignature,
  handler as ColourHandler
} from '@tools/sass/functions/colours

module.exports = new Config()
  .merge({
    module: {
      rules: [
        {
          test: /\.scss$/,
          use: [
            ...
            { loader: 'sass-loader',
              options: {
                sourceMap: true,
                functions: {
                  [ColourSignature]: ColourHandler
                }
              }
            },
          ]
        }
      ]
    }
  })

# src/your-package.js

import Colours from '@tools/constants/colours'
import "./your-styles.scss"

export default YourAwesomeComponent {
  static Colours = Colours
}

export const colours = Colours

# src/your-styles.scss

.your-awesome-component { 
  background-color: ColourGet(veganvomit, sobrightithurts);
}

# tools/sass/functions/colour.js

import Colours from '@tools/constants/colours'

export signature = 'ColourGet($name, $shade: default)'
export handler = function(name, shade) {
  const colour = Colours[name]

  if (!colour) return 

  if (typeof colour === 'string') return colour

  return colour[shade]
}

# tools/sass/constants/colours.js

export default {

  veganvomit: {
    sobrightithurts: "darkkhaki",
    light: "#D2691E",
    default: "#8B4513",
    somethingsomethingsomethingdarkside: "#000"
  }

}

So now when you publish your package, they can access sass variables from your default export YourAwesomeClass.Colours or they can import it directly `import { Colours } from 'your-awesome-package'

Answer 2

I highly recommend using webpack-merge to separate out your Sass config to make it easy for other packages to use it. For your current config, I would do three things:

1. Add webpack-merge to your project (npm i --save-dev webpack-merge).

2. Put your Sass config into a separate file, named something like webpack.sass-config.js. Have it include the following:

   var ExtractTextPlugin = require('extract-text-webpack-plugin');
   
   exports.config = function(options) {
     return {
       module: {
         loaders: [
           {
               test:   /\.(scss|sass|css)$/,
               loader: ExtractTextPlugin.extract("style", "css!sass")
           },
           {
               test: /\.scss$/, loader: 'style!css!sass!sass-resources'
           }
         ]
       },
       plugins: [
         new ExtractTextPlugin("[name].css")
       ]
     }
   }
   
   // Side note: returning a function instead of a plain object lets
   // you pass optional parameters from your main config file. This
   // is useful if you want to make something like your compiled css
   // file name different for another Webpack project without having
   // to edit your Sass configuration file.
   

3. Update your webpack.config.js to the following:

   var merge = require('webpack-merge');
   
   // import your separated Sass configuration
   var sassConfig = require('webpack.sass-config');
   
   // Define your common config for entry, output, JSX, fonts, etc.
   var common = {
     entry: ['./src/index.js'],
     module: {
       loaders: [
         {
           test: /\.jsx?$/,
           exclude: /node_modules/,
           loader: 'babel'
         },
         {
           test: /\.(png|woff|woff2|eot|ttf|svg)$/,
           loader: 'url-loader?limit=10000&name=fonts/[hash].[ext]'
         }
       ]
     },
     resolve: {
       extensions: ['', '.js', '.jsx']
     },
     output: {
       path: __dirname + '/build',
       publicPath: '/',
       filename: 'index.js',
       library: 'Supernova',
       libraryTarget: 'umd'
     },
     externals: {
       'react': 'react',
       'react-dom': 'react-dom'
     }
   };
   
   // Merge your common config and Sass config
   var config = merge(
       common,
       sassConfig.config()
   );
   
   // Export the merged configuration
   modules.exports = config;
   

Obviously, this can go far beyond just your Sass config. I use webpack-merge to separate my development config from my production config. This article on Survive JS is a great resource for how to make the most of your Webpack setup.