webpack.config.dev.js

const webpack = require('webpack');
const path = require('path');
const HTMLWebpackPlugin = require('html-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = {
  entry: `${__dirname}/index.js`,
  output: {
    path: `${__dirname}/dist`,
    filename: 'bundle.js',
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: ['babel-loader'],
      },
      {
        test: /\.(jpeg|png|jpg)$/,
        use: 'file-loader',
      },
      {
        test: /\.scss$/,
        include: path.resolve(__dirname),
        use: ['style-loader', 'css-loader', 'sass-loader'],
      },
    ],
  },
  resolve: {
    extensions: ['*', '.js', '.jsx'],
  },
  plugins: [
    new CopyWebpackPlugin([{ from: 'public/assets', to: 'assets' }]),
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify('development'),
    }),
    new HTMLWebpackPlugin({
      template: './public/index.html',
    }),
    new webpack.HotModuleReplacementPlugin(),
  ],
  devServer: {
    contentBase: './dist',
    hot: true,
  },
};