Add formatters: fullDateWithWeekday, weekday and weekdayShort

[philipbulley]

I'd like to request a few additional formats to be added as follows:

/** Localized full date with weekday, useful for accessibility @example "Tuesday, January 1st, 2019" */
fullDateWithWeekday: TLibFormatToken;

/** Weekday format string @example "Wednesday" */
weekday: TLibFormatToken;

/** Short weekday format string @example "Wed" */
weekdayShort: TLibFormatToken;

Why?

I'm creating a Date Picker (for React Native) and feel its important for accessibility that the weekday, month, day, and year can be read out aloud by a screen reader.

Why not just pass a custom format string?

I don't want end-users of the date picker to have to pass in a custom formatter string to achieve this, simply because accessibility is often ignored and this issue will rarely be visible to developers. We really need to ship with a good default.

Why aren't the existing defaultFormats suitable?

• fullDate outputs January 1st, 2019 and doesn't contain the weekday
• normalDateWithWeekday outputs Wed, Jan 1st and as such is not suitable for screen readers due to the abbreviations of weekday and month
• There are no defaultFormats that can output the weekday alone which would otherwise allow a suitable string to be built through multiple format() calls

@dmtrKovalenko, if you're fine with this addition, I'd be happy to submit a PR.

[dmtrKovalenko]

@philipbulley thanks for this issue! we definitely need it.

It will be really cool if you will open PR with functionality. Thanks ❤️

[philipbulley]

@dmtrKovalenko I've also just noticed that the existing fullDate doesn't work as per the docs.

Given these docs:

/** Localized full date, useful for accessibility @example "January 1st, 2019" */
fullDate: TLibFormatToken;

The tests have assertions that don't match the example in the docs:

date-io/__tests__/formats.test.ts

Line 40 in e8ce35c

${"fullDate"} | ${"Feb 1, 2020"} | ${"1 февр. 2020 г."}

Making fullDate unsuitable for accessibility and screen readers as month abbreviations are used.

If you're not keen on making a breaking change here, would it be a good idea to introduce formatters named a11yFullDate and change the proposed fullDateWithWeekday to a11yFullDateWithWeekday? I'm happy to make the changes as part of #400, just let me know what you'd prefer.

[dmtrKovalenko]

There is keyboardDate that is suitable for keyboard input. But agree that it should be more default behavior

[philipbulley]

date-io/packages/core/IUtils.d.ts

Lines 42 to 43 in e8ce35c

	/** Localized keyboard input friendly date format @example "2019/01/01" */
	keyboardDate: TLibFormatToken;

Yeah, I'm thinking more about text-to-speech, as such Tuesday, January 1st, 2019 would be more suitable than 2019/01/01.

I think the problem above can be resolved by improving the docs, which I've now done in the PR.

[dmtrKovalenko]

Already released