Date filter can't format date/time with newlines

[ashsearle]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
Using a date format containing a newline is treated as though the format ended at the newline.
i.e. | date: 'dd MMM\nyyyy' is treated as though it were | date: 'dd MMM'

Plunkers: Angular 1.5.10, Angular 1.6.3, Angular 2.unknown

What is the expected behavior?
The format string should be processed in its entirety.

What is the motivation / use case for changing the behavior?
A UI design required a timestamp to be formatted with date and time separated by a newline. This should be as simple as | date: 'yyyy-MM-dd\nHH:mm' (assuming an appropriate CSS white-space value.)

Which versions of AngularJS, and which browser / OS are affected by this issue? Did this work in previous versions of AngularJS? Please also test with the latest stable and snapshot (https://code.angularjs.org/snapshot/) versions.
Appears to affect all versions of since at least March 2012, including angular 2

Other information (e.g. stacktraces, related issues, suggestions how to fix)
Fix in pull request #15792

[Narretz]

I see this more as a feature to be honest. And the workaround you posted is not that bad. But since the change is simple ... let's see what others say.

[ashsearle]

I'd argue it's a bug as you can't even embed newlines using escapes. Documentation doesn't mention this limitation:

format string can contain literal values. These need to be escaped by surrounding with single quotes (e.g. "h 'in the morning'").

I don't see why "h 'in the\nmorning'" shouldn't be expected to work.

(Incidentally, while trying alternative escape sequences like \u000a, I found modern unicode escape syntax like \u{0a} breaks horribly... Angular does not like that at all...)

[frederikprijck]

I'd say it's a feature and not a bug, as docs clearly state:

format string can be composed of the following elements:

followed by a list which does not include what you're talking about (no it doesn't mention a limitation, but it explicitly lists what you can use).

Leaving this aside, I wouldn't say it hurts adding this even though I'd think the use-cases for this are limited.

[ashsearle]

A little further investigation: newlines are handled in the first 'token' of the format string.

These work: | date: '\'Line 1\n\'yyyy' or even | date: '🤡\nyyyy'.
These don't: | date: 'yyyy\'\nLine 2\'' or even | date: 'yyyy\n🤡'.

Is that a feature, or is it a bug?

The docs are probably missing a description of how 'other characters' are handled (including characters actually used in the US-default date format strings: e.g. colons, commas, slashes, spaces etc.)

Perhaps the docs need to include this, as used in other libraries - for example:

PHP:

Unrecognized characters in the format string will be printed as-is

Or Java:

All other characters are not interpreted; they're simply copied into the output string during formatting...

[gkalpak]

I would say this is obviously a bug in the DATE_FORMATS_SPLIT RegExp (and #15792 looks like the correct fix).

Also, 👍 on updating the docs to mention that unrecognized characters are printed as-is (or something similar).

[Narretz]

Ok, then let's go with the PR