gistfile1.txt

// Children component, handleClick in props
const BodyOverlay = ({ handleClick }) => (
  <div className="body_overlay" onClick={handleClick} />
);

// propType checking
BodyOverlay.propTypes = {
  handleClick: PropTypes.func.isRequired
};

// Parent component
class App extends Component {
   state = {
    isMenuOpen: false
  }
  // set function
  handleClick = () => {
    this.setState({
      isMenuOpen: !this.state.isMenuOpen
    });
  }
  
  render() {
    return (
      <div className="layout" >
        <BodyOverlay handleClick={this.handleClick} />
      </div>
    )
  }
}