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import React from 'react'
import { useRouter } from './router'
const nextjsRouteAnnouncerStyles: React.CSSProperties = {
border: 0,
clip: 'rect(0 0 0 0)',
height: '1px',
margin: '-1px',
overflow: 'hidden',
padding: 0,
position: 'absolute',
top: 0,
width: '1px',
// https://medium.com/@jessebeach/beware-smushed-off-screen-accessible-text-5952a4c2cbfe
whiteSpace: 'nowrap',
wordWrap: 'normal',
}
export const RouteAnnouncer = () => {
const { asPath } = useRouter()
const [routeAnnouncement, setRouteAnnouncement] = React.useState('')
// Only announce the path change, but not for the first load because screen
// reader will do that automatically.
const previouslyLoadedPath = React.useRef(asPath)
// Every time the path changes, announce the new page’s title following this
// priority: first the document title (from head), otherwise the first h1, or
// if none of these exist, then the pathname from the URL. This methodology is
// inspired by Marcy Sutton’s accessible client routing user testing. More
// information can be found here:
// https://www.gatsbyjs.com/blog/2019-07-11-user-testing-accessible-client-routing/
React.useEffect(
() => {
// If the path hasn't change, we do nothing.
if (previouslyLoadedPath.current === asPath) return
previouslyLoadedPath.current = asPath
if (document.title) {
setRouteAnnouncement(document.title)
} else {
const pageHeader = document.querySelector('h1')
const content = pageHeader?.innerText ?? pageHeader?.textContent
setRouteAnnouncement(content || asPath)
}
},
// TODO: switch to pathname + query object of dynamic route requirements
[asPath]
)
return (
<p
aria-live="assertive" // Make the announcement immediately.
id="__next-route-announcer__"
role="alert"
style={nextjsRouteAnnouncerStyles}
>
{routeAnnouncement}
</p>
)
}
export default RouteAnnouncer
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