反应：useState() 与 useRef()

Question

I've gone through the React Docs once.

I'm trying to compare useState() with useRef() in my mind…

Commonalities to both useState() and useRef():

• Available in functional components only
• Create static values – value persists between function calls
• Values are mutable
• Are scoped within their function component
• Scope includes other hooks (use's) within their function component

Differences between useState() and useRef():

• useState triggers re-render, useRef does not.
• useRef can reference child elements (via “ref={}”), useState can't.
• For child DOM elements, ref={} refers to the DOM element itself.
• For child React components, ref={} refers to the child component itself.

…And this previous Stackoverflow question adds:

• useState updates it's value asynchronously, useRef updates synchronously.

So I have 3 questions so far:

1. Are the above commonalities & differences correct?
2. Any other commonalities or differences I should be aware of?
3. From the component that creates the reference (useRef+ref={}), can I both get & set values on the child component (yes, it may/may not be wise to do so)?

Answer 1

Basically your comparison is correct, but as already was mentioned in comments they serve different purposes. You just need to know is that useRef basically is syntax sugar :

useRef() is basically useState({current: initialValue })[0]