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A Note on NextJS Router's Assertive Announcements

This is a quick note on a potential NextJS pitfall for accessibility engineers regarding it's router announcements.

I recently discovered a bug during some accessibility verification testing that was specific to NextJS and the way it's router works.


At a high level (forgive me, NextJS devotee's) each time the user clicks a NextJS link the framework mimics browser behavior by changing the page's URL and sending out an announcement for screen reader users by pushing an update to it's announcer component that has a role="alert" and aria-live="assertive".


I was testing a flow where the user finds themselves on a page with a category of products. There are buttons at the top of the page that act as sub-filters for the categories (think going from Drinks to Sodas for example). As the user filters the page there is a number displayed that tells them visually how many results their filters have produced. Since the look of the page was very SPA like (no big chunky refresh etc), my assumption was this number should be an ARIA live region. In particular a polite one (please always be polite).

The previously mentioned sub filters weren't SPA button's updating the page's content at all. They were links to distinct page's that represent a set of filters with search results in the application. And each time one was clicked the page's new route was announced by the NextJS router's assertive live region. The number was updated as well, since going from "Drinks" to "Soda" will yeild fewer results, But the aria-live="polite" region's announcement was getting clobbered by the assertive router announcement. This took a little bit of research on my part because I was unfamiliar with NextJS's accessibility features in particular their router's ARIA live region.


ARIA is for screen reader users. From the perspective of a screen reader user the SPA like nature of the page is totally lost. What they hear is search results and links that take them to more precise results. So the decision was made to ditch the live region on the number updating the product count. Because each filter is a link to a new page the product count isn't dynamic content that is changing under the user and needs to be updated. It's just content on the new page the screen reader user needs to explore and orient themselves on.