index.js

module.exports = function() {
  return {
    presets: [
      [
        "@babel/preset-env",
        {
          useBuiltIns: "entry",
          corejs: 3,
          modules: process.env.BABEL_ENV === "esm" ? false : "cjs",
          exclude: ["transform-typeof-symbol"]
        }
      ],
      ["@babel/preset-react", { useBuiltIns: true }]
    ],
    plugins: [
      ["@babel/plugin-proposal-class-properties", { loose: true }],
      ["@babel/plugin-proposal-object-rest-spread", { useBuiltIns: true }],
      [
        "@babel/plugin-transform-runtime",
        {
          corejs: false,
          helpers: false,
          version: require("@babel/runtime/package.json").version,
          regenerator: true
        }
      ],
      "@babel/plugin-transform-object-assign"
    ]
  };
};