react.dev/examples/update-on-async-rendering/invoking-external-callbacks-before.js

// Before
class ExampleComponent extends React.Component {
  // highlight-range{1-13}
  componentWillUpdate(
    nextProps,
    nextState
  ) {
    if (
      this.state.someStatefulValue !==
      nextState.someStatefulValue
    ) {
      nextProps.onChange(
        nextState.someStatefulValue
      );
    }
  }
}