.babelrc

{
  "plugins": [
    "@babel/plugin-transform-react-jsx",
    "@babel/plugin-proposal-class-properties"
  ],
  "sourceMaps": true,
  "env": {
    // Note this applies to the Jest tests:
    "test": {
      "plugins": ["@babel/plugin-transform-modules-commonjs"],
      "presets": [["@babel/preset-env", { "targets": { "node": "current" } }]]
    }
  }
}