Prevent profile form submission when required fields are empty

[vijendrajat]

On the user profile screen, required fields (Email and Nickname) are validated server-side. If a user spends time filling out many fields but leaves a required field empty and submits, WordPress returns a server-side error and all unsaved field values are lost.

This fix adds client-side validation to the profile form using the existing validateForm() function already available in common.js. The form-required class is added to the Nickname and Email rows in user-edit.php, and a submit event handler is added to #your-profile in user-profile.js that calls window.validateForm() to block submission and highlight the empty fields. Server-side validation is unchanged and remains the security boundary. Only the #your-profile update form is targeted, matching the server-side behavior where Nickname is only required on update.

Trac ticket: https://core.trac.wordpress.org/ticket/41314

Use of AI Tools

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

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[softglazee]

Tested locally on Windows (Docker, Chrome, 7.1-alpha trunk) after a clean npm ci + npm run build:dev — the fix works as intended: submission with empty Nickname/Email is blocked client-side, both fields get the error highlight, and unsaved values in other fields are preserved. Valid data saves normally in a single click.

One minor issue: each blocked submit activates the spinner next to the Update Profile button and it's never reset, so spinners accumulate on repeated attempts (screenshot attached). Since the button is at the bottom and the highlighted fields are at the top, there's no feedback near the button about why nothing happened. Suggest resetting the spinner in the handler when validation fails, and possibly moving focus/scrolling to the first invalid field.

Full test notes on the Trac ticket: https://core.trac.wordpress.org/ticket/41314#comment:17