webpack.dev.js

const path = require('path');
const { merge } = require('webpack-merge');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

const common = require('./webpack.common');

module.exports = merge(common, {
  mode: 'development',
  devtool: 'eval-source-map',
  devServer: {
    hot: true,
    open: true,
    static: path.resolve(__dirname, 'src')
  },
  module: {
    rules: [
      {
        test: /\.(scss|css)$/,
        use: [
          MiniCssExtractPlugin.loader,
          {
            loader: 'css-loader',
            options: {
              sourceMap: true,
              importLoaders: 1
            }
          },
          {
            loader: 'postcss-loader',
            options: {
              sourceMap: true,
              postcssOptions: {
                plugins: [
                  ['autoprefixer']
                ]
              }
            }
          },
          {
            loader: 'sass-loader',
            options: {
              sourceMap: true,
              implementation: require('sass')
            }
          }
        ]
      }
    ]
  }
});