In the past the @babel/polyfills was used, but it became obsolete. It's necessary to manually import the polyfills if needed.
For this case we have created package react-union-polyfills.
To use stable polyfills, import importPolyfills function from react-union-polyfills in root package
import { importPolyfills } from 'react-union-polyfills';
If you need to support Internet Explorer 11, run function importPolyfills.ie11() within ready function of root package
ready(() => {
importPolyfills.ie11();
justRender(<Root />);
});
To support Internet Explorer 9, run function importPolyfills.ie9() instead of importPolyfills.ie11() as mentioned above. Support for IE11 will be added automatically.