Fix: Controlled form inputs reset on form submission

[rdanciu11]

Summary

Fixes controlled form inputs incorrectly resetting after form submission with form actions.

Fixes

• Fixes [React 19] Controlled checkboxes are reset by form submission and form.reset() #31695
• Fixes [React 19] Controlled <select> component is subject to automatic form reset #30580

The Bug

When a form with a function action is submitted, controlled form inputs (those with checked or value props) are incorrectly reset to their default values. This breaks the expected behavior where controlled inputs should maintain their state.

Affected input types:

• Text inputs (<input type="text">)
• Select elements (<select>)
• Textareas (<textarea>)
• Checkboxes (<input type="checkbox">)
• Radio buttons (<input type="radio">)

The Fix

Enhanced resetFormInstance() in ReactFiberConfigDOM.js to:

1. Check React's internal fiber tree to determine if an input is controlled
2. Examine memoizedProps for control props:
   • value prop for text inputs, select elements, and textareas
   • checked prop for checkboxes and radio buttons
3. Skip reset for controlled inputs
4. Only reset truly uncontrolled inputs

This ensures controlled inputs maintain their state after form submission while uncontrolled inputs still reset as expected.

Tests

Added comprehensive test coverage in ReactDOMForm-test.js:

Controlled inputs (should NOT reset):

• Controlled checkboxes don't reset on form submission
• Controlled radio buttons don't reset on form submission
• Controlled select elements don't reset on form submission
• Controlled textarea elements don't reset on form submission

Uncontrolled inputs (should still reset):

• Uncontrolled checkboxes still reset correctly
• Uncontrolled select elements still reset correctly
• Uncontrolled textarea elements still reset correctly

All existing tests continue to pass

How Has This Been Tested?

• Ran full test suite: yarn test ReactDOMForm-test
• Verified reproduction case scenarios
• Tested with both controlled and uncontrolled inputs across all affected input types

[albr74]

Hi @rdanciu11 There is a bug "similar" to this #30580
Please, can you see it?. Perhaps the solution is similar to your approach.

[rdanciu11]

Hi @albr74. Actually, my implementation should already take care of that too because it checks React's fiber tree for control props (value or checked) rather than targeting specific element types.

I will write some tests right now to make sure.

I wasn't aware of issue #30580. Thanks for the heads up.

[rdanciu11]

Update: I've confirmed the fix works for select elements and added tests

I've updated this PR to include tests for:

• Controlled select elements (fixes [React 19] Controlled <select> component is subject to automatic form reset #30580)
• Controlled textarea elements
• Controlled checkboxes
• Controlled radio buttons
• Uncontrolled inputs still reset correctly

The fix works across all these input types because it checks React's internal fiber tree for control props (value or checked) rather than special-casing specific element types. I've also updated the PR title and description to reflect the biggerscope.