React usePortal hook

Creates a portal, allowing rendering of children outside the parent component.

• Use the useState() hook to create a state varible that holds the render() and remove() functions for the portal.
• Use ReactDOM.createPortal() and ReactDOM.unmountComponentAtNode() to create a portal and a function to remove it. Use the useCallback() hook to wrap and memoize these functions as createPortal().
• Use the useEffect() hook to call createPortal() and update the state variable any time el's value changes.
• Finally, return the render() function of the state variable.

const usePortal = el => {
  const [portal, setPortal] = React.useState({
    render: () => null,
    remove: () => null,
  });

  const createPortal = React.useCallback(el => {
    const Portal = ({ children }) => ReactDOM.createPortal(children, el);
    const remove = () => ReactDOM.unmountComponentAtNode(el);
    return { render: Portal, remove };
  }, []);

  React.useEffect(() => {
    if (el) portal.remove();
    const newPortal = createPortal(el);
    setPortal(newPortal);
    return () => newPortal.remove(el);
  }, [el]);

  return portal.render;
};

const App = () => {
  const Portal = usePortal(document.querySelector('title'));

  return (
    <p>
      Hello world!
      <Portal>Portalized Title</Portal>
    </p>
  );
};

ReactDOM.render(<App />, document.getElementById('root'));