fix: disable tab for outside days (#1567)

[DanielJKelly]

Context

Please see #1567 for more context about the issue this PR is meant to fix.

Analysis

The issue is that const isFocusTarget = Boolean(focusContext.focusTarget && isSameDay(focusContext.focusTarget, day)) will return true for multiple days if there is a day that is both "selected" and "outside".

If a day is both outside and selected, the equivalent "inside" day must also be present on one of the displayed calendars, so this day will receive tabIndex=0 and there is no need for the outside version of the day to have tabIndex=0.

Solution

Per the above analysis, my solution is to not consider a day with both the selected and outside active modifiers as a focus target, meaning the tabIndex will be set to -1.

[DanielJKelly]

"If a day is both outside and selected, the equivalent "inside" day must also be present on one of the displayed calendars"

I just realized this is not true, whoops. Perhaps I could check if the day is within more than one displayed month 🤔

[DanielJKelly]

"If a day is both outside and selected, the equivalent "inside" day must also be present on one of the displayed calendars"

I just realized this is not true, whoops. Perhaps I could check if the day is within more than one displayed month 🤔

I updated the PR to check if a day is both outside and displayed, which I think makes sense.

[gpbl]

Hey @DanielJKelly thanks for your PR, I've been investigating #1567 too and this one seems a good solution.

If a day is both outside and selected, the equivalent "inside" day must also be present on one of the displayed calendars,

I want to give a second look: I'm not 100% sure of this (yet) :)

[gpbl]

I think we don't need to check if the date is displayed or not. I'd just check the activeModifiers.outside.

Suggested change

	!isOutsideAndDisplayed
	!activeModifiers.outside

[gpbl]

@DanielJKelly Thanks for your investigation! I could review your PR and apply some changes:

• disabled tabIndex for outside days
• added an integration test for your use case

I think we should fix this in getInitialFocusTarget, but this function is not aware of the outside days yet.

What do you think? Am I missing something if we don't check "displayed days"?

[DanielJKelly]

@DanielJKelly Thanks for your investigation! I could review your PR and apply some changes:

• disabled tabIndex for outside days
• added an integration test for your use case

I think we should fix this in getInitialFocusTarget, but this function is not aware of the outside days yet.

What do you think? Am I missing something if we don't check "displayed days"?

@gpbl Thanks for the feedback and making the changes. I think you are right that checking "displayed days" is unnecessary. I only added that extra check because I wasn't completely sure if there was some use case I was missing for having an outside day be focusable.