webpack.config.dev.js

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  // the output bundle won't be optimized for production but suitable for development
  mode: 'development',
  // the app entry point is /src/index.js
  entry: path.resolve(__dirname, 'example', 'index.js'),
  output: {
  	// the output of the webpack build will be in /dist directory
    path: path.resolve(__dirname, 'build'),
    // the filename of the JS bundle will be bundle.js
    filename: 'bundle.js',
  },
  module: {
    rules: [
      {
      	// for any file with a suffix of js or jsx
        test: /\.jsx?$/,
        // ignore transpiling JavaScript from node_modules as it should be that state
        exclude: /node_modules/,
        // use the babel-loader for transpiling JavaScript to a suitable format
        loader: 'babel-loader',
        options: {
          // attach the presets to the loader (most projects use .babelrc file instead)
          presets: ["@babel/preset-env", "@babel/preset-react"]
        }
      }
    ]
  },
  devServer: {
    historyApiFallback: true,
    contentBase: './',
    hot: true
  },
  // add a custom index.html as the template
  plugins: [new HtmlWebpackPlugin({ template: path.resolve(__dirname, 'example', 'index.html') })]
};