What is the difference between "onTouched", "onChange" and "all" modes?

[guillermomorini]

They seem to behave the same.

From what I can tell, they both trigger after onBlur and onChange.

for all vs onChange, when would one trigger, but not the other?

[agammann]

The difference is easiest to see before the first submit, on a field that hasn't been blurred yet:

Mode	Change before first blur	First blur	Changes after first blur
onChange	Validate	Don't validate from blur alone	Validate
all	Validate	Validate	Validate
onTouched	Don't validate yet	Validate	Validate

So onTouched lets someone type without showing validation immediately, then starts validating once they've left the field. all also validates blur events; onChange responds to changes instead.

I checked a registered input with React Hook Form 7.89.0, without submitting it. For change → blur → change → blur, the cumulative validation counts were:

onChange:  1, 1, 2, 2
all:       1, 2, 3, 4
onTouched: 0, 1, 2, 3

After submission, also consider reValidateMode, which defaults to onChange and can make modes appear similar when revalidating errors. With a Controller, make sure its field.onBlur reaches the input. See the mode documentation.