[React: parent/child reference] #react

child.js

class Child extends Component {
  static defaultProps = {
    onRef: undefined
  }

  componentDidMount() {
    this.props.onRef(this);
  }

  componentWillUnmount() {
    this.props.onRef(undefined);
  }
  
  render() {
    
  }
}

Child.propTypes = {
  onRef: PropTypes.func
};

export default Child;

parent.js

class Parent extends Component {
  componentDidMount() {
    if(this.child) {
    	this.child.setState(/* ... */);
    }
  }
  
  render() {
    return (<Fragment><Child onRef={(ref) => { this.child = ref; }} /></Fragment>);
  }
}