Validating an input field while it's still focused is like a teacher repeatedly interjecting "this is no complete sentence" before the students have finished their sentence.

I couldn't agree more!

field being in focus doesn't mean I'm not done. field not being in focus doesn't mean I'm done.

focus alone is a very bad criterium

I hate when they don’t give instructions on how to format and leave you guessing

Well yeah, gotta make sure that users are stressed as much as possible. Just add a slow and cpu intensive validation to make the input feel janky.

Then add confusing error messages and just for fun add an A/B test on the form that is broken half the time.

Bonus points if you "forget" to add any useful contact information to your website/app.

Just give the address of some remote island.

It's very typical of UI designer these days. Not only they perform task on each key press (inside an input field), they even remove the submit button.

@daniel-wu

No submit/validate/save button is the death of me.

You mean when I initialize the variable but the IDE is immediately telling me that it isn't used anywhere while i am still initializing/typing it?

Don't forget to make the error box shake with every key press

OTOH, imagine you're applying for a grant. The 1st field asks for revenue. Then you find out it's too high... after you filled 60 other fields.

@cprn that's fine if a field gets validated when I have proceeded to the next form field, but not while I haven't finished typing (e.g. Error! USD 5,- is not enough money to ask for)