[UX] Add a token-browser-like PHP date format helper dialog

[klonos]

This is a spin-off from #4536.

@BWPanda

There's a bit of scrolling needed to find the actual table of formats, and no way to link straight to it from what I can see. Since I doubt those formats would change much, I wonder if it'd be better for us to create our own page to link to...? Either in Backdrop itself (in a modal like the tokens one), or on b.org/api.b.org.

@jlfranklin

The Date/Time Format Help module will include the documentation directly on the "Add date format" page.

[stpaultim]

This sounds like a great idea.

[ghost]

Related: https://github.com/backdrop/backdrop-issues/issues/1284

[ghost]

Here's a PR that adds a fieldset of common date/time codes: https://github.com/backdrop/backdrop/pull/4007

It was inspired by the Date/Time Format Help contrib module, though not a direct integration (I figured we don't need to show all codes on this page, just the common ones, then link to PHP's manual for the rest).

[indigoxela]

Cool, love it!

Some suggestions:

• It could also be a details element, as this help item is new
• It might make sense to collapse it initially
• If the locale/language modules are enabled, one can "localize" these formats, but on that page the help isn't provided (/admin/config/regional/date-time/formats/long/localize)

That's all optional.

[ghost]

Thanks for the suggestions.

• What's the difference/benefit of 'details' over 'fieldset'?
• I was about to say that I considered collapsing by default, but didn't see any benefits in doing so (considering there's nothing below to scroll to), but then I checked and the submit button is down there! So yes, we can either collapse by default, or (preferably) move the fieldset below the submit button...
• Indeed, we should add there too.

I'll work on updating the PR, but not now. It's ~g:ia~ 10:46pm, so I'm off to bed 😉

[bugfolder]

What's the difference/benefit of 'details' over 'fieldset'?

The details element is supported natively in browsers, IIRC. We used it for a similar use case of "additional information", for the "How layouts work" expandable information on /admin/structure/layouts.

[ghost]

PR updated to:

• Use <details> instead of <fieldset>
• Move the PHP codes below the form submit button
• Add the PHP codes to other forms as well:
  • 'Localize' tab for date formats
  • 'Logging and errors' form (/admin/config/development/logging)
  • Views' date fields (only visible when date format set to 'custom')

[indigoxela]

Many thanks for updating. Still love it, although I find it a bit odd that the help for a form item appears sort of outside the form.

Are we doing it that way somewhere else in core?