Exercise 07: Validate a local practice form
Use a copy of examples/07. Enter only invented values.
A. Explain
Why listen to submit on the form instead of only click on the submit button? Why does preventDefault not prove that a value is valid?
B. Diagnose
Remove the input listener that clears the custom name error. Trigger an empty-name error, then type Demo Visitor. Observe when the next submit refreshes it. Restore the listener so the custom state updates during correction.
C. Transfer
Add a checkbox labeled “I understand this is a local practice check” with required. Do not add a name attribute or any outgoing request. Verify empty, malformed email, whitespace name, quantity 0, quantity 1.5 and a valid synthetic submission.
Evidence
Record which case failed and the correction needed. A successful check must stay on the same page and say nothing was sent or registered.