How to keep the previous value if not NULL

Language used: javascript with react

I have made a custom HOOK to keep the previous state

here my custom hooks

import { useEffect, useRef } from 'react';

export const usePrevious = (value) => {
  const ref = useRef();
  useEffect(() => {
    ref.current = value;
  }, [value]);
  return ref.current;
};

here where I am using it :

export const ArticleQuantity = () => {
  const [quantity, setQuantity] = useState(1);
  const prevQuantity = usePrevious(quantity);

  useEffect(() => {
    console.log(prevQuantity + quantity); 
  }, [quantity]);

<div>
  <input
  onChange={(e) => setQuantity(e.target.value)}
  defaultValue={quantity}/> 
<div>
}

Problem : if my user enter "3" in the input and then remove the "3" to enter "5", my previous state will be "null" because the last value is removed.

How can i keep "3" instead of null ?

Thank you.

>Solution :

Add a condition to check null

  useEffect(() => {
    if(value){ 
      ref.current = value;
    }
  }, [value]);