webpack.config.js

const webpack = require('webpack');
const path = require('path');
const postcssPresetEnv = require('postcss-preset-env');

module.exports = {
  plugins: [
    new webpack.ProvidePlugin({
      $: "jquery",
      jQuery: "jquery"
    })
  ],
  entry: {
    main: './source/assets/javascripts/index.js'
  },
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules)/,
        loader: 'babel-loader'
      },
      {
        test: /\.scss$/,
        use: ['style-loader', 'css-loader', 'sass-loader']
      },
      {
        test: /\.css$/,
        use: [
          'style-loader',
          { loader: 'css-loader', options: { importLoaders: 1 } },
          {
            loader: 'postcss-loader',
            options: {
              ident: 'postcss',
              plugins: () => [
                postcssPresetEnv({
                  autoprefixer: { grid: true }
                })
              ]
            }
          }
        ]
      },
      {
        test: /\.(jpg|jpeg|png|gif|svg|eot|ttf|woff|woff2)$/i,
        use: ['file-loader']
      }
    ]
  }
};