Why useFormState vs formState?

[GollyJer]

Just upgraded to v7. Most of the issues/bugs I had with v6 related to defaultValues. I'm happy to report they are all fixed! 🚀

My question now is why would one choose to use userFormState vs formState from useForm?
Is it purely if you have multiple forms in a large application? In that case why wouldn't accessing formState from each individual form provide the same level of optimization.

I'm clearly missing something here so I thought I'd ask.

My entire usage of react-hook-forms is on single-screen, single-form, react-native screens with the Controller component.
Can I benefit from userFormState?

Thanks!

[bluebill1049]

useFormState is at the component level, doesn't trigger re-render at the root. I think we should make this clearer in the doc.

The same applies to watch vs useWatch. it's better to use those hooks if you have a large and complex forms.

[bluebill1049]

Take a look at this example: https://codesandbox.io/s/calc-i231d?file=/src/App.tsx which i have used useWatch and the caculation re-render will only happen at the component, leave the root component peacefully.

[zhixuan-loh]

If we are accessing formState from a useFormContext, will useFormState give me performance improvement?

[hjiog]

I think it's not possible. Once control._subjects.state change, it will trigger useForm change, so I think useFormState and formState produce the same effect.