[React 19] allow opting out of automatic form reset about react

[chungweileong94]

The automatic form reset in React 19 actually caught me off guard, where in my case, I was trying to validate the form inputs on the server, then return & display the input errors on the client, but React will reset all my uncontrolled inputs.

For context, I wrote a library just for doing server-side validation https://github.com/chungweileong94/server-act?tab=readme-ov-file#useformstate-support.

I know that you can pass the original input (FormData #28754) back to the client, but it's not easy to reset the form based on the previously submitted FormData, especially when the form is somewhat complex, I'm talking about things like dynamic items inputs, etc.

It's easy to reset a form, but hard to restore a form.

[pawelblaszczyk5]

I think you should return current values from action in such case and update the default value 😃

[glo85315]

@adobe export issue to Jira project PWA

[officialyashagarwal]

I think you should return current values from action in such case and update the default value. and return required!

[zce]

This is very necessary in the step-by-step form, such as verifying the email in the auth form first

[tranvansang]

Be careful to handle if the action throws an error, your "returning the new default" at the end of the function will be ineffective.

#29090

[chungweileong94]

Now that I have played with React 19 form reset for a while, I think this behavior kind of forces us to write a more progressive enhancement code. This means that if you manually return the form data from the server and restore the form values, the user input will persist even without JavaScript enabled. Mixed feelings, pros and cons.