webpack.config.js

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

module.exports = {
  entry: "./src/index.js",
  output: {
    filename: "main.js",
    path: path.resolve(__dirname, "build"),
  },
  module: {
    // exclude node_modules
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: ["babel-loader"],
      },
    ],
  },
  // pass all js files through Babel
  resolve: {
    extensions: ["*", ".js", ".jsx"],
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: path.join(__dirname, "public", "index.html"),
    }),
  ],
  devServer: {
    static: {
      directory: path.join(__dirname, "build"),
    },
    port: 3000,
    // Allow all Code Sandbox preview domains
    allowedHosts: [".csb.app"],
  },
};