isDirty should align with other libraries

[alexqhj]

isDirty flips to true when you change any form value, but doesn't return to false when the state returns back to default values.
I'm unsure about the reasoning for this behavior.

Here's an example using Tanstack Form.
https://stackblitz.com/edit/tanstack-form-1cspfar1?file=src%2Findex.tsx

The docs specify:

Important note for users coming from React Hook Form: the isDirty flag in TanStack/form is different from the flag with the same name in RHF. In RHF, isDirty = true, when the form's values are different from the original values. If the user changes the values in a form, and then changes them again to end up with values that match the form's default values, isDirty will be false in RHF, but true in TanStack/form. The default values are exposed both on the form's and the field's level in TanStack/form (form.options.defaultValues, field.options.defaultValue), so you can write your own isDefaultValue() helper if you need to emulate RHF's behavior.`

But there's no explanation of the reason for this choice. But it was apparently unusual enough to warrant its own note in the docs.

If isDirty can't, or won't be changed, perhaps there's a way to expose a value indicating that the form is no longer in its default state. This is very useful for disabling submit buttons for example.

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

Perhaps it would be appropriate to
Option 1: Return isDirty to it's well known behavior of returning to false when the form is at its default values.
Option 2: As option 1, but isPristine is no longer a mirror of isDirty, but rather isPristine will be false when any change to the form has been made.
Option 3: Expose a new property, like isModified or isChanged to indicate that the values differ from the default/initial values.

[nimo23]

I really think the current behavior of isDirty is a bug - the explanation in the docs doesn't make it any less of a bug.

I mean, if isDirty == true, even if the field values ​​in the end are actually not changed from their original state, then TanStack form is giving us wrong information because isDirty = true is just wrong.

Therefore, the current behavior of isDirty feels like a bug..

[ioson]

i just run into this and think there should be a way to check for a changed form state.
The current implementation is confusing.

Either change isDirty or add isModified or isChanged as alexqhj suggested.