Useref in react interview question

1.What is useRef in React?

Answer: useRef is a React hook that returns a mutable object (.current) whose value persists across re-renders.

Example: const myRef = useRef(null);

2.What’s the difference between useRef and useState?

useState triggers re-renders when updated.

useRef does not trigger re-renders when .current changes.

3.When should you use useRef instead of useState?

When you want to store values that:

Don’t affect rendering.

Should persist between renders (like timers, previous values, DOM references).

4.How does useRef help in accessing the DOM?

useRef stores a reference to a DOM element that you can access directly.

Example: myRef.current.focus() to focus an input.

5.What happens if you update a useRef value? Does the component re-render?

No. Updating .current does not cause re-render.

6.Difference between useRef and createRef?

createRef is re-created on each render (used in class components).

useRef persists the same object between renders.

7.Can useRef be used to store previous state values?

Yes, by manually updating .current inside useEffect.

8.Can you pass useRef between components?

Yes, but usually with forwardRef to expose refs from child to parent.

9.What is the initial value of a useRef object?

Whatever you pass inside useRef(initialValue) → stored in .current.

10.Why is useRef called a “box” object in React docs?

Because .current acts like a box where you put a value and retrieve it without triggering re-renders.