const Child = forwardRef((props, ref) => {

  const [color, setColor] = useState("red");

  // To customize the value that the parent will get in their ref.current: 

  // pass the ref object to useImperativeHandle as the first argument. 

  // Then, whatever will be returned from the callback in the second argument, 

  // will be the value of ref.current. 

  // Here I return an object with the toggleColor method on it, for the parent to use:

  useImperativeHandle(ref, () => ({

    toggleColor: () => setColor(prevColor => prevColor === "red" ? "blue" : "red")

  }));

  return <div style={{backgroundColor: color}}>yo</div>;

});

​

​

class Parent extends Component {

  childRef = createRef();

  handleButtonClicked = () => {

    // Ref passed to a function component wrapped in forwardRef.

    // Note that nothing has changed for this Parent component

    // compared with the class component in example 2!

    this.childRef.current.toggleColor();

  }

  render() {

    return (

      <div>

        <button onClick={this.handleButtonClicked}>toggle color!</button>

        <Child ref={childRef} />

      </div>

    );

  }

}

const Child = forwardRef((props, ref) => {

  const [color, setColor] = useState("red");

  // To customize the value that the parent will get in their ref.current: 

  // pass the ref object to useImperativeHandle as the first argument. 

  // Then, whatever will be returned from the callback in the second argument, 

  // will be the value of ref.current. 

  // Here I return an object with the toggleColor method on it, for the parent to use:

  useImperativeHandle(ref, () => ({

    toggleColor: () => setColor(prevColor => prevColor === "red" ? "blue" : "red")

  }));

  return <div style={{backgroundColor: color}}>yo</div>;

});

​

​

class Parent extends Component {

  childRef = createRef();

  handleButtonClicked = () => {

    // Ref passed to a function component wrapped in forwardRef.

    // Note that nothing has changed for this Parent component

    // compared with the class component in example 2!

    this.childRef.current.toggleColor();

  }

  render() {

    return (

      <div>

        <button onClick={this.handleButtonClicked}>toggle color!</button>

        <Child ref={childRef} />

      </div>

    );

  }

}

const Child = forwardRef((props, ref) => {

  const [color, setColor] = useState("red");

  // To customize the value that the parent will get in their ref.current: 

  // pass the ref object to useImperativeHandle as the first argument. 

  // Then, whatever will be returned from the callback in the second argument, 

  // will be the value of ref.current. 

  // Here I return an object with the toggleColor method on it, for the parent to use:

  useImperativeHandle(ref, () => ({

    toggleColor: () => setColor(prevColor => prevColor === "red" ? "blue" : "red")

  }));

  return <div style={{backgroundColor: color}}>yo</div>;

});

​

​

class Parent extends Component {

  childRef = createRef();

  handleButtonClicked = () => {

    // Ref passed to a function component wrapped in forwardRef.

    // Note that nothing has changed for this Parent component

    // compared with the class component in example 2!

    this.childRef.current.toggleColor();

  }

  render() {

    return (

      <div>

        <button onClick={this.handleButtonClicked}>toggle color!</button>

        <Child ref={childRef} />

      </div>

    );

  }

}