isDirty should flip back to false when default values are equal

[alexqhj]

Describe the bug

isDirty flips to true when you change any form value, but doesn't return to false when the state returns back to default values.

For most if not all form libraries I've used, the expected behavior is the form is not dirty when the default values is equal. See formik example here:
https://stackblitz.com/edit/react-hooks-form-validation-example-formik-hh9rdieb

Tanstack Form already exposes the isTouched property which can be used to determine if the form has been touched. It appears right now that both isTouched and isDirty now have the same behavior. Except when you reset the form, dirty returns to false as expected.

Your minimal, reproducible example

https://stackblitz.com/edit/tanstack-form-1cspfar1?file=src%2Findex.tsx

Steps to reproduce

1. Type in to the input
2. See that the form is dirty
3. Remove the value from the input
4. See that the form remains dirty
5. Reset the form
6. See that the form is no longer dirty

Expected behavior

1. Type into the input
2. See that the form is dirty
3. Remove the value from the input (effectively resetting it)
4. See that the form is no longer dirty

How often does this bug happen?

None

Screenshots or Videos

No response

Platform

• Windows
• Chrome Version 131.0.6778.140

TanStack Form adapter

None

TanStack Form version

0.40.2

TypeScript version

No response

Additional context

No response

[thazlett16]

This is documented in the field-state section.

In your example if you add the isTouched prop with your isDirty flag, isTouched will change to true when you focus the input and then remove focus from the input field (without changing the value).

[alexqhj]

This is documented in the field-state section.

In your example if you add the isTouched prop with your isDirty flag, isTouched will change to true when you focus the input and then remove focus from the input field (without changing the value).

That's not what I'm referring to.
Even the docs say:

and "dirty" after the value has been changed

Changed, not modified.

A-B (the value has changed. I.e it's dirty)
A-B-A (the value hasn't been changed, i.e not dirty, but touched)

If the field returns to its original value, is it still dirty? All libraries I've worked with so far says no, it's only touched. Dirty is only true if the values differ from the initial value(s).

[thazlett16]

I'm not a maintainer so not sure for their reasoning but just wanted to point you to the right spot for the different lifecycles. Under the image of that link for field-state they say:

the isDirty flag in TanStack/form is different from the flag with the same name in RHF.

If you want to keep the issue open and talk to them about why that is the case that is fine. Just wanted to point you in the right direction!

[alexqhj]

Yeah I think it warrants a discussion. I'd love to hear the reasoning behind this deviation, as the behavior of isDirty seems to be a well established in many well known form libraries. I'll reopen this as a question instead.

[devth]

Discussion continues at #1081 (I have the same question).