Things have changed with v5, but if this is still a problem, we can address it.

I'm not understanding your concern. In your demo, you should just be doing the toUpperCase().trim() in the format function. I'm not understanding why you would want to call onChange first?

I've updated to v5 and this still seems to be an issue.
See updated small demo of where this is needed.
We have a stand alone email input component that shows the suggested domain while typing.
It then updates the email to the suggested domain onBlur by calling the onChange with the suggestion. (This is a standard form field that an work with any form).
We are wrapping this input with final-form and would like to trim the email onBlur by passing formatOnBlur to the final-form Field.
The issue is that the format function still have the value as the email without the suggested domain
so it formats that and the suggestion never gets set.

I've implemented what I understand your requirements to be:

1. No whitespace around email address (trim())
2. Autocomplete should work
3. Product name should turn to all uppercase on blur

Did I miss any?

You don't need formatOnBlur for the email address.

With the example, it wouldn't allow spaces to be typed.
For a states auto complete, that would not work. We would need to allow typing a space and therefore would have to have the format only formatOnBlur.

See updated state auto complete demo

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Merging #465 into master will not change coverage.
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  Coverage     100%   100%           
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@erikras Thanks for checking into this!
I've updated this pr to work with v6..

I don't doubt that this fixes your problem, but I'd like to have a test that demonstrates the problem and fails with this code commented out, but passes with it included. Either you can do it, or I can try to get around to it later this week...

Your test is pretty good, but it's not, the parlance of the React Testing Library motto, "how a user would use the library". Primarily: handleBlur would not have access to "fire event" on the input DOM node.

Why, why, why you'd want to call imperatively onChange inside the onBlur? this sounds like a misusage to me, but maybe I'm just not aware about the use case - would be good to describe it 🤔

I agree that this feels wrong somehow. I'll have to give more thought to the motives behind this change. It also created an untested code branch. I'm not sure when the ternary on line 115 would ever flip the other way.

Published in v6.3.0.

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