govuk-frontend

Update date input to use `type=text` and `inputmode=numeric`

#1704

Merged

Within the date input component the individual inputs look like this:

<input […] type="number" pattern="[0-9]*">

We set the input to type="number" so that Android browsers display a numeric keypad keyboard when the input is focussed.

iOS uses the full alphanumeric keyboard for type="number", so we add pattern="[0-9]*" which triggers the numeric keypad there too. This is technically invalid HTML, as the pattern attribute only applies to inputs of type text, search, url, tel and email, but is not known to cause any real-world issues.

However, there are a number of known issues with inputs of type="number" – many of which were found in research and documented by @hannalaakso :

• they silently discard non-numeric input in Chrome (except the letter 'e')
• users can accidentally increment or decrement the number using the arrow keys without realising
• users can accidentally increment or decrement the number using the scroll wheel on the mouse or the scroll gesture on their trackpad
• they appear as unlabeled in NVDA's element list
• in NVDA's object navigation they are seen as a spin button which has an edit field and two buttons inside. Those buttons are unlabeled, but decrease/increase the value
• when tabbing to the field NVDA using pressing nvda+tab they are reported as unlabeled edit fields
• users of Dragon Naturally Speaking cannot dictate into them as expected

(Bugs have been filed where appropriate)

In testing, using <input […] type="text" inputmode="numeric" pattern="[0-9]*"> mitigates these issues, with some minor drawbacks:

• Between iOS 12.2 and 13.0, the numeric keypad with punctuation is displayed instead of the numeric keypad. Versions prior to 12.2 do not support inputmode, thus fallback to the pattern attribute, and continue to show the full numeric keypad. iOS 13 updates inputmode="numeric" to use the numeric keypad without punctuation.
• Firefox, UC Browser (and older versions of other browsers) on android support neither inputmode nor pattern, and so will use the full alphanumeric keypad until those browsers introduce support for inputmode. (Note: neither Firefox nor UC browser on Android are listed in our own browser support matrix nor the service manual)

Closes #1700

Great work, long time coming. Love the list of references that back this change.