React custom hook

gistfile1.txt

import { useState, useEffect } from 'react';
const useWindowSize = () => {
  // IMPLEMENT
  const [size, setSize] = useState({width: window.innerWidth, height: window.innerHeight});
  useEffect(() => {
    const eventResize = () => {
    	setSize({width: window.innerWidth, height: window.innerHeight});
    }
    
    window.addEventListener('resize', eventResize);
    
    return window.removeEventListener('resize', eventResize);             
  });
  
  return size;
}
 
// usage
const App = () => {
  const size = useWindowSize();
 
  return (
    <div>
      {size.width}px / {size.height}px
    </div>
  );
}