Update to use a11y script module package in Core.

[sirreal]

See WordPress/wordpress-develop#7304.

What?

Update the interactivity-router package to always use the @wordpress/a11y module for its aria-live regions.

This was behind a Gutenberg-only flag, but since landing in Core in 6.7 (with compatibility in Gutenberg for previous versions) the flag can be removed to always use the a11y module.

Why?

It's preferable to use the shared package that implements this functionality instead of a one-off implementation. Now that a11y is available as a script module, it should be used.

How?

Remove the IS_GUTENBERG_PLUGIN conditionals.

Testing Instructions

This PR is difficult to test on its own because it requires the package to be updated as a Core dependency for proper testing. It does not affect Gutenberg behavior, only the package's behavior in Core. There are other ways of doing it but this works:

• Get a checkout of Core from Interactivity Router: Update for latest GB changes. wordpress-develop#7304. This is the build that will be running.
• Run npm ci in the Core checkout to install packages.
• Build the package from this PR (npm run build:packages in Gutenberg).
• Replace the @wordpress/interactivity-router package in Core's node_modules (node_modules/@wordpress/interactivity-router) with the package directory in Gutenberg (remove the directory and copy the directory from Gutenberg packages/interactivity-router).
• In Core, run the npm build script you use, in my case npm run dev.

Then test out that the interactivity router a11y functionality is working. A good way to test is the query block with "force page reload" option disabled. Specifically, the aria-live regions of the page should be updated (with localized text if in non-English locale) announcing "Page loaded."

[github-actions]

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Co-authored-by: sirreal <jonsurrell@git.wordpress.org>
Co-authored-by: gziolo <gziolo@git.wordpress.org>
Co-authored-by: michalczaplinski <czapla@git.wordpress.org>

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[gziolo]

Just confirming, does this state come from the server in WP 6.6 and 6.5? Was it removed in WP core for WP 6.7?

[sirreal]

WordPress/wordpress-develop#7304 is expected to remove it in 6.7 and switch to the script module data passing. It was in the Interactivity API store state before that change, so in WordPress 6.6 it was in the Interactivity API store state.

[gziolo]

Excellent. Thank you for confirmation.

[sirreal]

I may not have answered that fully. Yes, it's server provided state in WordPress 6.6.

[michalczaplinski]

I'm testing using the "Testing Instructions" from PR description (using Core https://github.com/WordPress/wordpress-develop/pull/7304/files + copied packages from this PR).

I see an odd issue: the aria-live message has a trailing &nbsp every other navigation:

output_6de84c.mp4

It might be something silly or even unrelated but let's confirm it first 🙂

[sirreal]

Thanks for the thorough testing!

I see an odd issue: the aria-live message has a trailing \n every other navigation:

This is expected behavior, the speak package adds a trailing   on repeated identical messages to encourage accessibility software to announce them:

gutenberg/packages/a11y/src/shared/filter-message.js

Lines 20 to 26 in 3b99bb6

	/*
	* Safari + VoiceOver don't announce repeated, identical strings. We use
	* a `no-break space` to force them to think identical strings are different.
	*/
	if ( previousMessage === message ) {
	message += '\u00A0';
	}

[michalczaplinski]

Looks great to me 👍 Thank you for working on this Jon!

[github-actions]

I just cherry-picked this PR to the wp/6.7 branch to get it included in the next release: 20ae57d