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

// After
class ExampleComponent extends React.Component {
  // highlight-range{1-8}
  componentDidUpdate(prevProps, prevState) {
    if (
      this.state.someStatefulValue !==
      prevState.someStatefulValue
    ) {
      this.props.onChange(this.state.someStatefulValue);
    }
  }
}