import { useEffect, useRef } from 'react';

/**
 * Usage:
 * const [count, setCount] = useState(0);
 * const prevCount = usePrevious(count);
 */
export default value => {
  const ref = useRef();
  
  useEffect(() => {
    ref.current = value;
  }, [value]);
  
  // Return previous value (happens before update in `useEffect` above)
  return ref.current;
}