The dependency array of useEffect, useCallback, useMemo

Question

I'm so confused of the dependency of React Hooks. Here's the example:

const memorizeValue = useMemo(() => {
    return {
      count,
      setCount,
    }
  }, [count, setCount])

In React documentary:

Note

The array of dependencies is not passed as arguments to the function. Conceptually, though, that’s what they represent: every value referenced inside the function should also appear in the dependencies array. In the future, a sufficiently advanced compiler could create this array automatically.

count and setCount both inside useMemo's callback, if i doesn't pass setCount in the dependency array, the eslint won't warning me, but count will, so what's the difference? why don't need pass setCount? setCount is inside useMemo, isn't it?

here's the codesandbox link:

https://codesandbox.io/s/react-codesandbox-forked-xfupk?file=/src/Demo1/index.js:254-363

I think i maybe misunderstand the document. Somebody point it out, thanks.

Answer 1

Check the useState docs

Note

React guarantees that setState function identity is stable and won’t change on re-renders. This is why it’s safe to omit from the useEffect or useCallback dependency list.

Assuming setCount is the updater function of a useState hook then it's guaranteed to be a stable reference.