webpack.config.js

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

module.exports = {
  entry: "./index.js",
  mode: "development",
  devtool: "source-map",
  output: {
    filename: "bundle.js",
    path: path.resolve(__dirname, "dist"),
  },
  devServer: {
    port: 8080,
    host: "localhost",
    open: true,
    hot: true,
  },
  externals: {
    react: "globalThis.React",
    "react-dom": "globalThis.ReactDOM",
    "react-16": "globalThis.React_16",
    "react-dom-16": "globalThis.ReactDOM_16",
  },
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: ["style-loader", "css-loader"],
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: [
          {
            loader: "babel-loader",
          },
          "source-map-loader",
        ],
      },
    ],
  },
  plugins: [new HtmlWebpackPlugin({ template: "./index.html" })],
};