React Hook Dependency Warning - Stale Closures

1. Variable used in effect but not in dependencies array
2. Function reference changes every render
3. Object/array in dependencies (equality always false)
4. Suppressing warning with eslint-disable instead of fixing
5. Not understanding effect lifecycle

Add all dependencies:

const [count, setCount] = useState(0);

useEffect(() => {
  console.log(count); // use count
}, [count]); // add to deps

Memoize dependencies to prevent re-creates:

const config = useMemo(() => ({ value: 10 }), []);
useEffect(() => {
  console.log(config.value);
}, [config]);