date picker component: Updated function to accept more date formats

[MalcolmVonMoJ]

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Issue or RFC endorsed by the maintainers

Increase date formats which are supported 🎉

Description of the change

Added 3 new regular expressions for new formats:

• International format yyyy-mm-dd
• Month names, e.g.
  • 29 February 1980
  • 29 Feb 80
  • 29 Chwefror 1980 (Welsh)
• Leading month names, e.g.
  • February 29, 1980
  • Chwefror 29ain, 1980 (Welsh)

Amended the existing RegEx to:

• Allow for inconsistent and longer separators (e.g. 29 / 02 /1980)
  • No change in the characters allowed to be separators, but this was necessary for the common format 29 February, 1980 where there is a comma and space in one separator but not the other.
• Allow for 2 and 4 character years
  • Will assume the year is between 1970 & 2069 inclusively if a 2 digit year is used.

Now, if any of these formats are used, the calendar will recognise the date if clicked open.

Alternative designs

I have tried to allow for all reasonable formats to be supported, to support copy-pasting of dates from anywhere into the input field.

Possible drawbacks

None unless I've made a mistake. The function is now more complex, has more regex etc. But the functionality of the date picker should not have been compromised in any way.

Verification process

We have a website which is using the date picker. I amended the code locally and tested it on that page. (Screenshot below - please ignore the slight colour differences, they are not part of this change.)

I tested it by typing in dates of various formats, and seeing whether the calendar recognised those dates by opening it and seeing that it defaulted to the date I had typed in. If it defaulted to today, then it hadn't recognised it.

I also typed in a number of dates which were in already-supported formats to ensure that these are still supported with the new code.

Release notes

Increase the number of accepted date formats to include 2-digit years and month names, including Welsh month names.