webpack.config.js

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

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  },
  module: {
    rules: [
      { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" },
      {
        test: /\.scss$/,
        use: ExtractTextPlugin.extract({
          fallback: "style-loader",
          use: ["css-loader", "postcss-loader", "sass-loader"]
        })
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin("styles.css")
  ]
};