react-instantsearch/examples/server-side-rendering/.babelrc

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "browsers": ["last 2 versions", "ie >= 9"]
        }
      }
    ],
    "@babel/preset-react"
  ],
  "plugins": ["@babel/plugin-proposal-class-properties"]
}