Date Format and Time Format: review the JavaScript part

[afercia]

In General Settings, Date Format and Time Format have a "Custom" radio button followed by a text field to enter a custom format. When using a keyboard or screen reader, when the text input field gets focused the related radio button gets selected.

Tabbing is the only way keyboard users and screen reader users have to navigate through a form, so they will very likely focus the text field but that doesn't mean they want to enter a custom format. They're just navigating the form.

To reproduce the worst scenario:

• use the keyboard to navigate
• once focus is on the first radio button in the group, use arrows to select your favorite format (not custom)
• now to exit the radio buttons group the only way is to tab again
• the text field gets focused and the radio button you previously selected isn't' selected any more
• keyboard users don't have a way to avoid this
• screen reader users, additionally, won't be even informed the selected radio button has changed

Worth considering to fix this in core whether or not the Settings Api Enhanced will get merged.

[rianrietveld]

Maybe we could have a last radio button called Custom format.
And below that an empty input field where the date format can be entered?
Same for time.
And maybe JS toggle that field, so it's only displayed when the custom Format radio button is checked.