<RouteAnnouncer> aria-live value can be selected.

[yamanoku]

I gave a presentation at JSConfJP titled "The past and future of accessible front-end development".
At that time, I learned about GatsbyJS's RouteAnnouncer.

When I saw the internal implementation, I thought that aria-live is currently set to assertive.
https://github.com/gatsbyjs/gatsby/blob/2.24/packages/gatsby/cache-dir/route-announcer-props.js#L16

It seems to be for the following reasons, according to past blogs.

This region has aria-live set to assertive because we want route changes to always interrupt whatever the screen reader is currently doing.

However, the WAI-ARIA 1.1 description says the following

Because an interruption may disorient users or cause them to not complete their current task, authors SHOULD NOT use the assertive value unless the interruption is imperative.

There may be some screen reader users who feel annoyed by the fact that GatsbyJS notifications are currently assertive.

So, my suggestion is that if there is a setting, why not allow the user to select the value of aria-live?

A hint is the vue-annoucer setting in Vue.js.
https://github.com/vue-a11y/vue-announcer/tree/next#custom-announcer-object-meta

Whether the default value should be one or the other is a matter of debate, but being able to choose will increase the chances of making it accessible 👍🏼