Configure webpack + babel simple project. Watch mode + source maps.

babel.config.js

module.exports = function (api) {
  api.cache(true);

  const presets = [ "@babel/preset-env" ];

  return {
    presets,
  };
}

Init webpack + babel test project

// CLI
// 1. yarn init
// 2. yarn add @babel/core @babel/preset-env babel-loader webpack webpack-cli webpack-dev-server --dev
// 3. Add webpack.config.js
// 4. Add babel.config.js
// 5. Add script '"watch": "webpack-dev-server"
// Enjoy <3

webpack.config.js

const path = require('path');

module.exports = {
  mode: "development",
  entry: './src/index.js',
  devtool: 'inline-source-map',
  module: {
    rules: [
      { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" }
    ],
  },
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist'),
  },
};