React stateless components with lifecycle proposal

HelloMessage.js

const HelloMessage = props =>
  <div>Hello {props.name}</div>;

{
  let isMounted = false;
  
  const focusAfterAfterOneSec = el => {
    setTimeout(() => {
      if (!isMounted) return;
      el.focus();
    }, 1000);
  }

  HelloMessage.componentDidMount = el => {
    isMounted = true;
    focusAfterAfterOneSec(el);
  };

  HelloMessage.componentWillUnmount = el => {
    isMounted = false;
  };
};